best biography of galileo

• NONFICTION BOOKS
• BEST NONFICTION 2023
• BEST NONFICTION 2024
• Historical Biographies
• The Best Memoirs and Autobiographies
• Philosophical Biographies
• World War 2
• World History
• American History
• British History
• Chinese History
• Russian History
• Ancient History (up to 500)
• Medieval History (500-1400)
• Military History
• Art History
• Travel Books
• Ancient Philosophy
• Contemporary Philosophy
• Ethics & Moral Philosophy
• Great Philosophers
• Social & Political Philosophy
• Classical Studies
• New Science Books
• Maths & Statistics
• Popular Science
• Physics Books
• Climate Change Books
• How to Write
• English Grammar & Usage
• Books for Learning Languages
• Linguistics
• Political Ideologies
• Foreign Policy & International Relations
• American Politics
• British Politics
• Religious History Books
• Mental Health
• Neuroscience
• Child Psychology
• Film & Cinema
• Opera & Classical Music
• Behavioural Economics
• Development Economics
• Economic History
• Financial Crisis
• World Economies
• Investing Books
• Artificial Intelligence/AI Books
• Data Science Books
• Sex & Sexuality
• Death & Dying
• Food & Cooking
• Sports, Games & Hobbies
• FICTION BOOKS
• BEST NOVELS 2024
• BEST FICTION 2023
• New Literary Fiction
• World Literature
• Literary Criticism
• Literary Figures
• Classic English Literature
• American Literature
• Comics & Graphic Novels
• Fairy Tales & Mythology
• Historical Fiction
• Crime Novels
• Science Fiction
• Short Stories
• South Africa
• United States
• Arctic & Antarctica
• Afghanistan
• Myanmar (Formerly Burma)
• Netherlands
• Kids Recommend Books for Kids
• High School Teachers Recommendations
• Prizewinning Kids' Books
• Popular Series Books for Kids
• BEST BOOKS FOR KIDS (ALL AGES)
• Ages Baby-2
• Books for Teens and Young Adults
• THE BEST SCIENCE BOOKS FOR KIDS
• BEST KIDS' BOOKS OF 2023
• BEST BOOKS FOR TEENS OF 2023
• Best Audiobooks for Kids
• Environment
• Best Books for Teens of 2023
• Best Kids' Books of 2023
• Political Novels
• New History Books
• New Historical Fiction
• New Biography
• New Memoirs
• New World Literature
• New Economics Books
• New Climate Books
• New Math Books
• New Philosophy Books
• New Psychology Books
• New Physics Books
• THE BEST AUDIOBOOKS
• Actors Read Great Books
• Books Narrated by Their Authors
• Best Audiobook Thrillers
• Best History Audiobooks
• Nobel Literature Prize
• Booker Prize (fiction)
• Baillie Gifford Prize (nonfiction)
• Financial Times (nonfiction)
• Wolfson Prize (history)
• Royal Society (science)
• Pushkin House Prize (Russia)
• Walter Scott Prize (historical fiction)
• Arthur C Clarke Prize (sci fi)
• The Hugos (sci fi & fantasy)
• Audie Awards (audiobooks)

Make Your Own List

History Books » History of Science

The best books on galileo galilei, recommended by paula findlen.

Possessing Nature: Museums, Collecting, and Scientific Culture in Early Modern Italy by Paula Findlen

The trial of Galileo by the Roman Inquisition was one of the most public confrontations between the new science emerging in the 17th century and the Catholic Church but, nearly 400 years later, there's still a lot of scope to argue what it was about. Here historian of science Paula Findlen , a professor at Stanford University, explains the endless fascination of Galileo Galilei, the Renaissance man who turned a telescope to the sky and took the world by storm, and recommends the best books to start learning more about him.

Interview by Sophie Roell , Editor

Life of Galileo by Bertolt Brecht

Galileo’s Telescope: A European Story by Franco Giudice, Massimo Bucciantini and Michele Camerota, translated by Catherine Bolton

Letters to Father: Sister Maria Celeste to Galileo by Suor Maria Celeste (Virginia Galilei) and Dava Sobel (editor and translator)

On Trial for Reason: Science, Religion, and Culture in the Galileo Affair by Maurice A. Finocchiaro

Dialogue Concerning the Two Chief World Systems by Galileo Galilei & Stillman Drake (trans.)

1 Life of Galileo by Bertolt Brecht

2 galileo’s telescope: a european story by franco giudice, massimo bucciantini and michele camerota, translated by catherine bolton, 3 letters to father: sister maria celeste to galileo by suor maria celeste (virginia galilei) and dava sobel (editor and translator), 4 on trial for reason: science, religion, and culture in the galileo affair by maurice a. finocchiaro, 5 dialogue concerning the two chief world systems by galileo galilei & stillman drake (trans.).

B efore we get to the books, a general question: in his lifetime, Galileo won celebrity status because of his telescope. What would you say was his biggest contribution as a scientist?

One is transforming the Dutch spyglass into a scientific instrument. He did not invent the telescope as an object, but he transformed a report of this object into an observational instrument. Astronomy changes, because of Galileo. It becomes observational in a different way. We extend sight with the help of instruments and use the telescope to see what we can see. That’s a major innovation.

Another is that Galileo’s mechanics is the foundation of a lot of basic high school physics . When we do inclined plane experiments, we’ve replicated some of his basic insights about how weight, mass, and motion behave—what became Galileo’s other lifetime work. People who study physics don’t forget this about Galileo, but others often do because of the infamy of his trial. They treat Galileo as if he died in 1633. But he lives another nine years and the thing that he is most concerned about during this period is the completion of his Two New Sciences , which is his mechanics. Galileo begins the process of really rethinking motion in ways that are very important for subsequent work, for instance, that of Isaac Newton .

Galileo also has very important comments on scientific methodology. The more his ideas are challenged, the more he thinks about scientific methodology, and ultimately writes this very interesting treatise called The Assayer that questions a lot of the presuppositions about how we know and what we know. Here Galileo is thinking about epistemology. In many ways it’s both a philosophical and a demonstrative piece of work.

Last, but hardly least, is his Letter to the Grand Duchess Christina . Galileo is probably the most important person trying to define the relationship between science and religion in writing, again, because he is put to the test about these things. His unpublished Letter to the Grand Duchess Christina , which he writes and really perfects in 1615 and begins to circulate is, today, a foundational document for people who are trying to understand the relationship between these two important ways of knowing and believing.

So, in spite of the trial, he was able to continue doing important science after 1633?

Yes, under great difficulty. He is under house arrest. He’s old and has a lot of health problems. He goes blind. But he also has loyal, younger colleagues who assist him. We sometimes forget his grit and determination to finish longstanding projects in this period. Also, from house imprisonment, he is able to protect and secure his reputation by getting books, like his prohibited Dialogue, translated into Latin and published in Protestant Europe. He has his Letter to the Grand Duchess Christina translated and published for the first time—not in Italy, obviously. It won’t be published in Italy until the 18th century, and even then it will be published illegally.

What do you think motivated him?

There are many different Galileos in the story of Galileo and that’s one of the reasons he’s such a fascinating figure. He’s human. He’s complex and he’s passionate and he’s arrogant and he’s egotistical and he’s smart and he’s insightful and he’s eloquent. But I think, fundamentally, what motivates Galileo and is probably the reason of his downfall—despite the fact that he’s savvy and a player, when the world starts to get to know him—is that he cares about the truth.

“Galileo’s mechanics is the foundation of a lot of basic high school physics”

He may at times seem to be prevaricating, but I think of him as somebody who, as a scientist, was fundamentally concerned with the science of motion. Astronomy is a long, productive and controversial diversion that interests him initially because it’s a place to explore problems of motion and a discipline full of unanswered questions. He is also somebody who likes to tinker, who likes machines, to know how things work. That combination is a natural for somebody perfecting an instrument that can assist in studying problems of motion by studying astronomy, so he becomes an astronomer.

Let’s look at the books you’re recommending for anyone wanting to learn more about Galileo, starting with the Bertolt Brecht play, Life of Galileo. Why do you like this and is it historically accurate?

First of all, there are three different versions of the Brecht play. That’s what is so fascinating. Brecht creates this play in three different contexts in the 30s, 40s and 50s. As a piece of interpretation, as a demonstration that there are many different Galileos that can be different kinds of object lessons, it’s amazing.

There are many inaccuracies. He takes license and liberty. Galileo has two daughters who are sent to a convent way too early for the older one to be thwarted in her marriage aspirations by Galileo’s increasingly controversial reputation, as Brecht would have us believe. But that’s a perfect dramatic move, so one can forgive Brecht for deciding that he has to do that. And who knows exactly how much he knew about the life of the daughters? After all, it’s only very recently, thanks to Dava Sobel’s work , that we know a lot about Galileo’s eldest daughter Virginia (Suor Maria Celeste).

Get the weekly Five Books newsletter

Nonetheless, I like Brecht. When you put aside both the deliberate decisions that he makes, the omissions and alterations and the things he just didn’t know in the way that a historian would, he does capture some things about Galileo as a person. He loved life. When the actor Topol played him, he really embodied this vision Brecht has of Galileo as a very human figure. That’s what theatre can do, it can bring that humanity to life in the same way that good fiction does. It’s also a performance and I think that Galileo and his world were naturally quite theatrical. Galileo was a contemporary of Shakespeare , after all.

Fundamentally, Brecht recognized that Galileo is not just of his times, but for the ages. As times change, we learn different things from him—and Brecht did. That’s why he kept rewriting the play. One version is for the Weimar Republic , on the eve of Nazi Germany , and as Brecht leaves that world. Another version is about the social responsibility of the scientist after the dropping of the atomic bomb. Another version is in the midst of the Cold War . By then Brecht is thinking about the American reaction to his own communism in the McCarthy era and becoming increasingly interested in migrating to Russia to explore these issues. In all of them, he can bring Galileo with him.

And it’s fun. I started reading it this afternoon and I was enjoying it.

Let’s go on to the second of the books you’ve chosen, which is Galileo’s Telescope: A European Story, written by three Italian historians of science, Massimo Bucciantini, Michele Camerota and Franco Giudice. Tell me why you chose it and what you like about it.

I’ve chosen this book because, first of all, it’s the combinatorial power of three really good Galileo scholars, who’ve thought long and hard about different aspects of Galileo’s work and his world. It’s three experts getting together and writing a book that is seamless, it doesn’t look like three different people wrote it, it’s very well integrated, it’s very accessible.

What I especially like is that it’s a real time story of the history of the telescope, which we don’t often get. What they decided to do was watch it unfolding like a news episode. How is this happening? Who is generating the news? How is the story of the telescope being transformed in each and every context? It’s not a story that starts with Galileo and it’s certainly not a story that ends with Galileo. Indeed, they leave us with a coda in which you see that the telescope has now travelled, via the commercial and the Jesuit missionary networks, all the way to India and to China. The telescope travels very far, in the early 17th century. In fact, when I was reviewing the book , I commented that by the late 17th century, people were using telescopes in the exploration of Baja California. They had been shipped to New Spain.

What the book gets you to do is to think about this as an object that has to travel through very concrete networks. At each stage, people respond to the fact of the telescope and to Galileo. It takes us back to a world of diplomacy and commerce. How does the telescope—through word of mouth, letters, relationships—travel through the networks that link different parts of the world?

I know they go way beyond this, but just focusing on the basics, I like the way at the beginning they have pictures of the telescope and explain the physical object he used. I think they say it’s 14x strength—so people really could see a lot more with this telescope than with the naked eye?

I think the original version was maybe eight to 10 times magnification. This is where Franco Giudice, who does a lot of work on the history of the instrument, comes in. They’re really good at getting you thinking about the problems of this telescope. Most of us have never used a replica of a Galilean telescope—we’ve used the kind of telescope that Kepler modifies, that changes how you view the image through a different combination of lenses. But at roughly the same magnification, cardboard replicas are kits for elementary school students. The first thing you learn is that you can’t even see the moon in its entirety through it, even with this magnification. You learn how narrow the focal point of the lens is and then you start realizing how many observations you would have to make before you could put together the description of the new things you see in the heavens that we see in Galileo’s Sidereal Messenger in 1610. You realize that he makes it look so easy when he presents his initial observations to the public, but it’s actually really hard work. To see Jupiter’s satellites—what Galileo calls the four moons of Jupiter—or the phases of Venus, is extremely difficult. That material insight into the limits of this new scientific instrument helps you understand that we have a lot of steps to go before we get to the Hubble telescope. Galileo has taken this very important first step, but he has to do a lot of hard work.

“Galileo was a great communicator of science to the public. He wanted to involve society in the project of science”

What they also help us understand is that critiquing Galileo is not just about resisting new ideas; this instrument doesn’t always work. The glass is made artisanally. Sometimes you get better lenses, sometimes you get worse, even when they’re crafted by Galileo. A seventeenth-century lense is artisan – it doesn’t come out the same each time. Even when he has made one, tested it, and sent it to someone else, they don’t have the benefit of all the hard work he’s done to generate observations. Everyone has to learn how to use this instrument, and they have to get a good version of it. Even then, there are still going to be questions about the implications of the ideas.

Bucciantini, Camerota and Giudice do an excellent job of showing that the questions are there from the start. It’s not simply a reactive thing that happens because Galileo pushes too hard, which is the simple version of the story. There really are a lot of questions and a lot of interest, even on the part of critics. What are people in places like Milan thinking about the telescope? There we see that the archbishop of the city, Federico Borromeo, is super interested in science. He is getting everything that’s new, but he’s also an archbishop. He’s a good example of how somebody outside of Rome is thinking along similar lines to what we see within Rome, that of course shaped the story of science and religion.

I don’t know whether it was in this book or another one, but the author(s) makes the point that everybody called it ‘Galileo’s telescope’ even though he hadn’t invented it. It was the telescope that make him an internationally renowned scientist, is that right?

Absolutely. This is why the news of the telescope is so important, because it’s also news of Galileo. Who was Galileo before he invented the telescope? He was a mathematics professor in his 40s who had published virtually nothing. He’d been teaching, people knew he was smart and interesting and witty and sarcastic. They knew that he had an agile mind. But he hadn’t done anything to gain the world’s attention. And then he did. I don’t think even he expected it to be as wildly popular, successful and controversial as it turned out to be.

Let’s move on to the third book you’ve recommended to learn more about Galileo, which is the letters that his oldest daughter sent to him, Letters to Father: Suor Maria Celeste to Galileo. She was sent to a convent age 13, which seems really sad. Can you explain the context of this and why you think these letters are important to read?

Galileo has three children with Marina Gamba, a woman he never marries. We don’t know a lot about this woman, so she’s been an object of some fascination. He has a son and he has two daughters. Virginia Galilei—with whom he has this correspondence—is the oldest daughter and perhaps the child who seems to be closest to his heart and most interested in what he does. They have a very loving relationship and we’re very fortunate that this half of the correspondence, her letters to him, have survived. And we’re all very sad that the other half of the correspondence has not survived, because then we would have the whole story of what really is a fascinating family dynamic.

First of all, we owe an enormous debt to Dava Sobel who not only wrote a book, Galileo’s Daughter , which if I were allowed to recommend six books I would recommend, but also had the insight to recognize that she should make her translation of the sources available. That’s not something a writer for a general audience often thinks of doing, and I want to fully credit her for having recognized not only that it would be great to write the story of Galileo from the perspective of his relationship with his oldest daughter, but that we should hear her in her own words.

Here again, we see a very human Galileo. We see a Galileo whose daughter loves him and worries about him, and who increasingly becomes aware of the problems that he’s facing, probably in ways that she hasn’t had to be until the trial occurs. We really get to know Galileo as a father, but also as somebody vehemently suspected of heresy while his own daughters, who are nuns, are praying for him. After he is condemned, Suor Maria Celeste demands access to read the terms of the condemnation and his abjuration, and then she volunteers to take on his penance of prayer. Shortly after they’re reunited, when he finally is allowed to return from Rome and comes to Arcetri—where he’s under house imprisonment and she’s in the convent nearby—she gets sick and dies. So the ending is tragic in ways that Brecht should have incorporated into his play. It was one of Galileo’s many tragedies.

Support Five Books

Five Books interviews are expensive to produce. If you're enjoying this interview, please support us by donating a small amount .

The story of Galileo’s daughter provides a lot of insight into this network of family and close friends who are very protective of him. Another moment I especially like in Galileo’s correspondence with his daughter is when, through this network of family and friends, he arranges for her to hand over the keys to his villa at Arcetri so that one of the trusted members of this larger family can go in and make some documents at least temporarily disappear. She may be a nun, but she does not hesitate to protect her father from further recriminations, should there be anything in the house that might get him into further trouble—or simply get lost if the Inquisition decides to come over and rifle through it. Some people have argued—and many of us now think—that it’s the manuscript of what becomes his Two New Sciences that is the thing they’re most concerned about. It goes ‘missing’, but it’s surely not the only part of his archive that disappears.

Another great moment in the letters is when she thinks about how she can use her female network to help her father. She’s outside of Florence, in this rather impoverished convent. They’re basically living a subsistence life: this is not one of these aristocratic convents in Florence, where people are eating jellied candies all day. But even from there she mobilizes all the women she knows. She imagines that maybe through talking to people, who can then intervene with the wife of the Florentine ambassador in Rome, she might assist her father in the problems that he’s having during the trial. That gives us some insight into the kind of person that she was, that she would reach out in these ways, as well as hand over the keys to her father’s house. She is actively trying to figure out what’s going on and what role she can play. I love this. We see a very different Galileo than if we just read his publications.

But why was he so poor that he had to put his daughter in a convent, if he was such a successful scientist? Do we know why he didn’t marry her mother?

We have no idea why they didn’t marry, the assumption is that she’s not of the appropriate social class, since he facilitates her marrying someone else in Padua after he leaves for Florence. Clearly the children matter a lot to him because he brings them all with him to Florence—and not her. Whatever the relationship was, marriage was never in the offing. But the children matter a great deal. He frets a lot over his son, who like so many sons of famous figures is not all his father would want him to be. With the girls, I think there is a problem about the cost of a dowry. It costs a lot less to give somebody a convent dowry than a dowry for marriage. I think there’s a decision made that it’s too costly to marry these daughters, that’s part of it. They are on the younger side when they take their vows. There’s been a bit of a rush. There’s also a clear sense that the youngest daughter, Livia, who’s known as Suor Arcangela, has some kind of psychic distress, she has some problems and that the older sister is looking after her. Maybe that was part of the bargain, too, that they couldn’t be separated. But, again, we have to read between the lines about why this all is. Did the oldest one ultimately have a spiritual vocation? Maybe, but no more or less than many women who enter convents under similar circumstances in this period.

Brecht presents him as desperate for money at the beginning of the play. Is that accurate then, that Galileo was always short of money?

One of the reasons he accepts this new position in Florence in 1610 is not only to go back to his native Tuscany, but because he hopes that it will be better financially and so better for his work, because he won’t have to be teaching and housing all these students. He’s very quick to cash in on the benefits of inventing the telescope. One senses he has a messy, needy family in which he is the best source of income for many people—like his brother, the musician, who then dies. He’s constantly having to bail people out.

Okay, we’re now at the fourth of the books you’re recommending on Galileo, a book which deals with the trial and his 1633 condemnation as a suspected heretic by the Roman Inquisition. It’s called On Trial for Reason and it’s by Maurice Finocchiaro, an emeritus professor of philosophy at the University of Nevada Las Vegas. The book is actually also quite a good introduction to Galileo in general, quite an opinionated one. Tell me why you chose it.

There are so many good books on Galileo and I hope these five will encourage people to read and dig in further. I’ve chosen this one because it was published recently, it came out in 2019. It’s specifically written for a general audience, but is by somebody, Maurice Finocchiaro, who has spent his life thinking about Galileo. Finocchiaro is a philosopher who is also deeply interested in the history of science, but has done more translating than almost anyone—save possibly for Stillman Drake (a great Galileo scholar of an earlier generation) and my colleagues Al van Helden and Eileen Reeves—and therefore has a very close and careful reading of Galileo’s words. When we want to read the documents of Galileo’s trial in English, and many allied documents, we turn to the works of  Maurice Finocchiaro. He’s spent his entire career thinking about Galileo. I want people to benefit from that long, hard thinking, because this is the kind of subject that deserves that.

What I like about On Trial for Reason is that it very economically gives you a lot of basic things that you want to know about Galileo. What exactly is the nature of Galileo’s scientific innovation? What has he done? What are the controversies? What are the problems of it from a scientific perspective, from a philosophical perspective, and then, of course, ultimately, from a religious perspective? He also reads the trial like a forensic analyst. He’s not a lawyer, he’s a philosopher, and he’s very interested in questions of logic. He does this logical analysis with the full benefit of a lot of the interesting new documents that have come to light over the last few decades, as people have done more and more archival research. Believe it or not, it’s still possible to find new documents related to the trial of Galileo. In fact, I just got an email this week from a young Italian researcher, Leonardo Anatrini, telling me about his forthcoming publication of one of the new documents that he found.

Finocchiaro is up to date on all the things that have happened up to the point the book is published, and he’s going to give you the full benefit of his reading these different, tricky, documents. For example, the famous injunction that Cardinal Robert Bellarmine personally gives to Galileo, in Rome, in 1616, after the Congregation of the Index has placed Copernicus’s On the Revolution of the Heavenly Spheres on the Index of Prohibited Books, pending its revision to conform with Catholic doctrine. Finocchiaro does a careful reading of this document that resurfaces during the trial that people have long forgotten about, and Galileo now has to reckon with. There have been many different interpretations of the slight differences in wording in the sparse documentation of this injunction by Robert Bellarmine. What did it really mean? What did he really say to Galileo? Why does it seem to be somewhat different in the inquisition’s archive versus Galileo’s own version? Finocchiaro does a very good job of sorting through these kinds of subtleties and discrepancies. That’s why I think this is a terrific starting point – then you can go from his reading of these things into the documents themselves.

And what’s his general conclusion? What was Galileo on trial for? It was a clash between science and religion—not in a simplistic way, obviously—but ultimately that’s what it was about.

That’s right. It goes back to the very thing that Galileo was trying to anticipate and provide his own answer for. I always tell my students that the trial of Galileo is like a murder mystery—except we already know who did it, we just don’t know what the crime was. What did he do? People have been asking this question ever since 1633.

Finocchiaro reminds us that the trial is a never-ending story. We’re still finding new ways to talk about it and rethink it. This is not a closed history, that happens and ends in 1633. It’s going to keep going, and we’re going to keep returning to it—and we need to look at the evolution of the ways people have responded to the trial ever since.

The title of the book reveals Finocchiaro’s understanding of the trial. Galileo’s use of reason over revelation, his foregrounding of the role of observation, of instruments, his definition of a hypothesis, his emphasis that when he is speaking hypothetically about something he is on a path to what he believes to be a better scientific truth: all of these things raise questions about the relationship between science and religion.

“I don’t think that Galileo, on his own, would ever have talked about religion and its relationship to science”

In 1543, when Copernicus published his book as a deathbed contribution, very few people—other than Copernicus himself—recognized that there might be a potential conflict. But that potential was written into the introduction of Copernicus’s book. It took almost a century to fully realize the level of the conflict that it engendered, that science is developing its own epistemology and its own path to truth, and that this may not fit comfortably with the way people understand nature from a religious perspective. In other words, if your point of reference is always how nature has been described in the Bible, and you allow no possibility for the distinction Galileo wishes to make—between why we write about nature in the Bible, for reasons of belief, versus how we write about nature, when understanding nature scientifically is our primary focus—what we see is a world of clashing expertise and, therefore, completely incompatible views about which truth to foreground.

Galileo’s way out of this is, I think, brilliant. He says, in the Letter to the Grand Duchess Christina , that two truths cannot contradict each other. Ultimately, he thinks that one has to trust that there will be a harmonious reconciliation, which is what the church believes nowadays. This is the great irony that Finocchiaro is really good at pointing out. What people refused to accept in Galileo’s own time we have accepted as a modern proposition. Not everyone, to be sure, but the Roman Catholic Church institutionally has accepted this since the end of the 19th century—and, in fact, moved towards it in stages ever since the trial of Galileo.

It ended badly for Galileo in the sense of he was under house arrest, but Giordano Bruno, who was also a Copernican, was burned at the stake. Why did Giordano Bruno end up dead and Galileo get off more lightly?

People have long puzzled over that. As a specialist, I will say that Bruno is an out-and-out heretic. First of all, he is an ex-Dominican who has not only left behind his religious order, but tried out every version of religion in Europe and been rejected or rejected himself from all of them. Then he returns to Italy, after having flirted with Protestantism in many different places. He’s a radical philosopher, a radical theologian. He believes in the plurality of worlds. I am quite confident that Galileo read Bruno and made sure to never once cite him explicitly because he understood how controversial that would be.

People still debate whether Galileo was actually a radical thinker from a religious perspective. Is he rejecting the Catholic Church? I have to say no, because there are many people in his world who do precisely that.  They tend to exit, if they can. Sometimes they come back, like Bruno, and challenge the church’s authority to define orthodoxy, and it ends badly. Galileo certainly could have fled. He could have stayed in Venice, where this might not have happened because while Catholic, Venice was very antagonistic to Rome. We’ll never know, of course. But Bruno sees Copernicanism as a kind of sign, he reads it allegorically. For him, it’s like an avatar. His The Ash Wednesday Supper , which is his most Copernican publication, is like a Renaissance Tao of Physics , if I can put it in those terms. He has a whole different style. He’s not interested in empiricism. He really is trying to create a new philosophy that also is tied to a new theology. He’s a radical thinker and utterly unrepentant about it.

“The more his ideas are challenged, the more he thinks about scientific methodology”

I don’t think that Galileo, on his own, would ever have talked about religion and its relationship to science. He was pressed to do so because, increasingly, the church was taking an interest in his science in a way that he didn’t like. He was trying to find a way out of this mounting difficulty.  Think of him as someone who finds himself at the center of a labyrinth and is trying to exit.

Returning to Brecht’s use of his condemnation at the trial and Galileo’s famous abjuration of everything he believed in—what kind of moment is this? Maybe Brecht’s vacillatio is a recognition that it’s hard to be an absolutely pure hero. And sometimes it’s hard—under these circumstances anyway—to be entirely a victim, let alone a collaborator. You’re all of the above.

Galileo certainly decided that he did not want to suffer the ultimate punishment for the conflict he has found himself in with the church. He wants détente, he wants to survive this moment. To do so, he has to demonstrate very publicly, in a way that is quite contrary to his intellectual beliefs and to his entire raison d’être, that he is an obedient Catholic more than anything else. So, he demonstrates that obedience in this official and public way and then he goes home and does a lot of things under house arrest that actually demonstrate quite the opposite. He gets into no trouble for it, even though he’s being closely monitored. That’s a really fascinating aspect of the story. This is something that Maurice doesn’t fully get into, but I’m especially fascinated with – what does it mean to live with the consequences of the trial for Galileo? For his society? For the church? How do they handle those initial years? What are people doing? No one ever calls him on his use of a network that allows his publications to appear in Protestant Europe, even those that are prohibited. Nobody ever says anything, even though it would have been fairly easy to trace some of this back directly to him if they wanted to.

And is that because the church recognizes that he’s probably right and so they’ll have to come around at some point?

Finocchiaro raises these issues in his book, as others have also done. Is Catholic regret there right from the start? We love to think of the Roman Inquisition as this bloodthirsty thing: they can’t wait to kill people. As I point out to my students, it’s bad PR for your religion to kill people. The best thing is to redeem and rehabilitate. Virtually no one really wants to do these things, least of all to Italy’s most famous scientist. He has already been given a lot of latitude—in 1616, he is warned but not condemned and his books are not put on the Index of Prohibited Books then, unlike 1633 when only one of his books is condemned this way. That’s important. There was an effort made to forestall what some of his most virulent critics already would have liked to see happen by 1616. Instead, it happens in 1633.

There are many different kinds of Catholics, even within the church, and that’s one of the things that you see in the story. Many people have accepted Galileo’s observations and the utility of the telescope; they recognize that these new observations might indeed open up new questions about how we understand the physical nature of the heavens, and that, over time, those questions might indeed lead us to want to discard old theories of the cosmos. They’re wondering what the implications will ultimately be for the relationship between cosmology as a scientific endeavour and faith. He’s hardly the only person thinking through these issues.

There are many Catholic astronomers who feel it was a mistake to condemn Galileo and who would have liked to see it otherwise. After the trial, there’s a reason the Vatican has an observatory, even today. Part of the legacy of the trial is that they become some of the great observational astronomers of the next couple of centuries. Many of them are actively trying to see if they can resolve some of the technical issues of observation that could be decisive in proving or disproving heliocentrism. At many moments, they think they’re almost on the verge of resolving these issues. Ultimately, though, you really do need better telescopes to be able to see and calculate things like stellar parallax. It is a matter of the time needed to develop the technology of a science and of course, the skills then to observe and calculate what you see. But there’s an enormous amount of optimism that if they just keep observing, eventually, they’ll be able to prove that Galileo is right.

“Critiquing Galileo is not just about resisting new ideas”

Catholic scholars lobby for a rethinking of Galileo’s condemnation, almost as soon as the trial ends. Maybe if I just talked to my friend in Rome, who really trusts me, he’ll see not only that this was wrong—maybe he already knows that this is wrong—and he will work with me to help figure out a way to resolve this. There were no easy answers for that in the short term. But, in the long term, by 1744, there are some concessions, as Finocchiaro discusses. The decision not to put any new books that advocate heliocentrism on the Index of Prohibited Books is important. It’s a sign of begrudging acknowledgment. Institutions are complex things. They move slowly, and they rarely acknowledge failure.

Let’s go on to the last book, which is actually by Galileo. The book of his you’ve chosen is The Dialogue Concerning the Two Chief World Systems . How many books did he actually publish?

Galileo  first published a pamphlet about his compass, Operation of the Geometrical and Military Compass. Many people forget that that was published before his Sidereal Messenger in 1610. There’s also a witty dialogue about seeing new stars (nova) that people have debated whether we should attribute to Galileo. That doesn’t appear under his own name, so we’ll put that aside though he was surely involved in it. Then he publishes his Letters on Sunspots in 1613, The Assayer in 1624, The Dialogue in 1632 and The Two New Sciences in 1638.

We should also count things published after the trial in Protestant Europe, like his Letter to the Grand Duchess , in 1636. It’s published after the trial, but not directly under his name, initially, so that’s also a little fuzzy.

Why did I pick The Dialogue ? I like all of Galileo’s books, they’re all fascinating. Fundamentally, Galileo was a great communicator of science to the public. He wanted to involve society in the project of science, to appreciate it, to support it, to understand it. And he had the literary skills to do so. He was, after all, a member of the Florentine literary academy as well as the scientific one. He loves poetry, music, and art. He’s a very cultured, talented and versatile figure. He brings all of this to his writing in each of his publications but, for me, The Dialogue is like reading Shakespeare. An entire world is in it. It’s not a scientific work in any normal sense, by our standard, or even by the standards of his own time. It’s like reading Plato and Shakespeare together, learning a lot about astronomy, and being very entertained while it’s going on and while it’s long, you read the whole thing. Then you understand what The Dialogue is. Galileo has mustered all of his knowledge and understanding of the resources of his society, of every moment in his life about science, but also every cultural moment that’s been meaningful, and he’s brought them all to bear in this very theatrical style of writing. What is The Dialogue , but a play by other means?

There are three characters and we get to know them, and also to love them, each in their own way. Two characters are named after two close friends from two different cities, who are both dead by 1633. He’s memorializing real friendships and even real conversations that he surely had over the years, not just with them, but with many, many, friends and colleagues. They each get to play a different role. The Florentine Salviati is a very committed Copernican and believes in heliocentrism. He’s all in and represents that view. Sagredo, named after a Venetian friend, is mostly persuaded but is constantly asking clarifying questions. He stands in for those of us who need to really understand and figure things out and aren’t just going to believe the first thing we hear because it’s a new and shiny prize. He’s willing to take the time to talk to people who are stubborn, and stick to their guns about old, outdated ideas, because Sagredo is the one who’s going to moderate their discussions with this third character called Simplicio. Yes, he could be named after an ancient philosopher, but one suspects it’s a joke and that this is the simpleton. This is part of what gets Galileo in trouble, being a little bit too funny with everything. Simplicio is a committed Aristotelian and not a sophisticated one. He’s the butt of the joke, he often doesn’t get the joke. He asks naive questions and doesn’t have profound insights. And yet, he allows us to see a position. Then, in essence, the fourth character in the story is Galileo himself, as the unnamed mathematician, who doesn’t get to speak but is discussed indirectly by the others as this kind of absent authority we might refer to. This book is the culmination of all of Galileo’s literary, philosophical and scientific aspirations for his astronomy.

And is it convincing in terms of the science? If we were back in the 17th century, and trying to figure out whether Galileo was right or not, should we be convinced by this book that the Earth does go round the sun and not vice versa?

We can see how friendly readers respond in surviving correspondence. And we can also witness an antagonistic reading by certain inquisitors in his trial documents.

Would we be convinced? Well, Galileo in this book builds a world over the days of his Dialogue , and many parts of it are quite persuasive, because they’re based on all his hard work with his instrument to observe the heavens. We should be convinced by what he says about the stars, the phases of Venus and the sunspots. Then we get to day four, and Galileo talking about his theories of the tides. And not only do we not find those convincing, from a scientific perspective, but many of his contemporaries did not think his theory of the tides was persuasive. As a culminating proof, it’s problematic.

There were many other problems about how people responded to The Dialogue, to be sure. But here Galileo’s desire to claim victory on everything—even on things that deserved a more careful reading—becomes his Achilles’ heel, not that the trial revolves around this, to be sure. He wanted the tides to prove the motion of the Earth in relationship to the sun; he basically excludes the Moon entirely. There is no lunar pull. He does this even though a careful reading of Kepler should have given him pause. Galileo does so because he thinks it’s too occult, it’s old, bad science to allow invisible forces to operate this way.  He misses the opportunity to rethink what the pull of the Moon is, what the physical relation is between the Moon, sun, and the Earth together.  And he also misses the opportunity to be much more empirical about the data he has on tides. People point out that the data he’s using on tides is not only incomplete, but even the data that he has, from places like Venice, if he’d read it more carefully, wasn’t adding up to what he argues.

“He’s complex and he’s passionate and he’s arrogant and he’s egotistical and he’s smart and he’s insightful and he’s eloquent”

So, here, we could say that he’s getting into an area of science, he hasn’t studied and thought through as carefully as he has observational astronomy. He leads with his desire to bring all these things together in one great culminating work. His instinct is right, but the science goes off in the wrong direction, and is incomplete.

From a literary perspective, it’s a perfect book. From a scientific perspective, it is a very interesting book that has a lot of sound insights, one big problem and a number of other unanswered questions. It is plausible, for many highly probable, but is it certain? This raises a philosophical question—and this is another way some inquisitors read the book and it is something that also interests Finocchiaro, by the way—of whether Galileo was a good philosopher. They say no, because he’s not following Aristotelian logic.  Of course he’s not, that’s not what Galileo wants to do! But they use that to critique the book, that this is not a work of good philosophy and that he’s failed the test of logic in a very formal sense. So that’s fascinating.

So he’s written a completely out of the box book, just like The Assayer is an unorthodox manifesto of his method and epistemology. There is no book like the Dialogue , even though there are dialogues that inspired it. Most of the others, we don’t think of as great literature—unless it’s Plato or Castiglione’s Book of the Courtier .

Did he have enough data to prove the Copernican system or not?

He had great preliminary data. The phases of Venus and his observations on sunspots are more decisive than the moons of Jupiter, spectacular as they are. They’re still trying to figure out what Saturn is. Galileo thinks it might have some moons as well. Later on, after his own lifetime, through some very interesting observational and deductive thinking, people figure out that, no, it’s a ring. That’s in the middle of the 17th century.

Galileo gives us many of the foundational building blocks and raises so many questions about traditional cosmology that there’s no going back. People at the time who criticize him about other things know that and there are very few pure Ptolemaic or Aristotelian philosophers wandering around Italy by 1633. Just to give you an example, by 1620 the Jesuits have decided that their official astronomy is that of Tycho Brahe, who is a Danish Lutheran. That’s perverse and yet it’s an important intermediate step. Tycho Brahe advocated for what’s called ‘geo-heliocentrism’ in which the Earth is still the stationary point of the cosmos, and the sun and the moon are going around the Earth, but all other planets revolve around the sun. Then you have to do these fancy calculations to make that work so they’re not colliding with each other.  It’s an awkward synthesis of the old and the new.

After all, if we think about this in the large scale of the cosmos—this was Kepler’s great insight—it’s all near the center. This is why Kepler writes science fiction, when he writes his Somnium and he imagines what the universe would look like from the Moon. He even does it with Mars, at one point. It’s all near the centre, mathematically, you can make it work, you just have to keep playing around. It’s harder from Saturn or anything further out, but anything that’s close to the centre can kind of be the centre. But that kind of playing around did not appeal to Galileo. He was a much more straightforward kind of thinker. I think that’s why he sometimes misses things that Kepler had much better insight into, like the elliptical path of planetary orbits. Galileo tells you in The Dialogue —that’s another thing that’s wrong­­—that everything moves in perfect circles. He’s still being more traditional than Kepler, who says, ‘No, it’s the circle and the line combined. It’s elliptical.’  He, not Galileo, begins to envision some invisible forces that produce this result, what Newton will call gravity.

So are you from a science background or a history background? Because to really understand Galileo, you need to be really on top of the science as well as the history.

Many of us in history of science come in with some combination of a background in science and history . I didn’t get my first degree in science. I’m one of those people who loved science in high school. Even when I entered college, I thought, ‘I’ll major in science, but also do something more humanistic.’ The problem was, I could never figure out which science I liked the most. What I found was that the history of science, especially the early history of science, was a wonderful place to ask these very foundational questions that we now take for granted and where there are not clear distinctions between disciplines. Galileo is such a great example. He is a Renaissance man, to use that classic phrase. He’s the son of a musician and his Dialogue is inspired partly by a dialogue his father had written between ancient and modern music that is part of the story of the birth of opera .

Galileo has interesting relationships with artists, he has strong opinions about what’s good literature. And he’s the great observational astronomer of his day who transforms this instrument into something productive, useful, and generative of an entire new way of thinking about astronomy. So he embodies that fluidity of disciplines. That’s what gives his Dialogue an especially distinctive flavour, because there’s not even a hint that it’s supposed to be a scientific textbook. That would be boring. It would be written in Latin and only for specialists (as Copernicus did) and be read by their students in the mathematics and astronomy classrooms of Renaissance Italy. Galileo wants to write for the world. He’s a very ambitious guy.

So are all his books written in Italian?

All of the works that he publishes directly are in Italian except for The Sidereal Messenger, which is in Latin. The reason is that he published his pamphlet on how to use his military and geometric compass in Italian in 1606 and one of the students, Baldassarre Capra, who took his tutorial, plagiarized it and published a Latin translation under his own name. Galileo then had an early intellectual property debate, where he asked the University of Padua to adjudicate in his favour, which they did. So, he’s already learned an important lesson—when you have a really valuable discovery and you publish it in your local language, somebody else can try to claim it. That was bruising, and it was recent and very fresh in his memory.

The telescope is a much bigger innovation than his compass. When he publishes the Sidereal Messenger, he deliberately chose to publish it initially in Latin because he wants it to be internationally received with no question that he is the author of this book, the person who has done these observations. In fact, he does this to such a degree that he actually erases the collaborations with his friends in Venice and Padua from the text, to their dismay, because he then takes a job elsewhere. So, he disses them on multiple levels. That’s another great thing about Galileo’s Telescope , the authors get you to see the way in which Galileo erases all of them, because he’s using this book to move on. It’s such a VC kind of story. It’s the IPO of 1610 and to do it he has to publish in Latin.

Then, the question is why he resumes publishing in Italian from 1613 till the end of his life. Doesn’t he want that international audience? Well, yes, but not in the same way. He sees these other publications as engaging the Italian-speaking public he is now cultivating after his celebrity in 1610. Galileo is a scientist who thinks a lot about the interface between science and society. When he writes The Sidereal Messenger , it has to be in Latin to be international, but when he wants people to appreciate the quality, style and flavour of his argument, he wants it to be in his own vernacular.  Ultimately, he is somebody who has not only read Dante and many other great Italian literary authors but he has also participated in the time-honoured Florentine project of calculating the shape and size of the Inferno (a lecture that he gives to the Florentine Academy). He’s very proud of his literary style and the way it communicates his ideas, not only to those who have some version of this as their written and spoken language, but also to foreigners who read and appreciate it. This is an era in which Italian is an international language of diplomacy and travel. He knows it’s not going to completely restrict his audience in the way that, say, Shakespeare’s English did at this time.

January 20, 2021

Five Books aims to keep its book recommendations and interviews up to date. If you are the interviewee and would like to update your choice of books (or even just what you say about them) please email us at [email protected]

Paula Findlen

Paula Findlen is Ubaldo Pierotti Professor of History and Professor, by courtesy, of French and Italian at Stanford University. She " teaches history of science before it was "science" (which is, after all, a nineteenth-century word). " In addition to many honours and awards, she was awarded Italy's international Galileo Galilei Prize in 2016 and is a fellow of the American Academy of Arts and Sciences.

We ask experts to recommend the five best books in their subject and explain their selection in an interview.

This site has an archive of more than one thousand seven hundred interviews, or eight thousand book recommendations. We publish at least two new interviews per week.

Five Books participates in the Amazon Associate program and earns money from qualifying purchases.

© Five Books 2024

• History Classics
• Your Profile
• Find History on Facebook (Opens in a new window)
• Find History on Twitter (Opens in a new window)
• Find History on YouTube (Opens in a new window)
• Find History on Instagram (Opens in a new window)
• Find History on TikTok (Opens in a new window)
• This Day In History
• History Podcasts
• History Vault

Galileo Galilei

By: History.com Editors

Updated: June 6, 2023 | Original: July 23, 2010

Galileo Galilei (1564-1642) is considered the father of modern science and made major contributions to the fields of physics, astronomy, cosmology, mathematics and philosophy. Galileo invented an improved telescope that let him observe and describe the moons of Jupiter, the rings of Saturn, the phases of Venus, sunspots and the rugged lunar surface. His flair for self-promotion earned him powerful friends among Italy’s ruling elite and enemies among the Catholic Church’s leaders. Galileo’s advocacy of a heliocentric universe brought him before religious authorities in 1616 and again in 1633, when he was forced to recant and placed under house arrest for the rest of his life.

Galileo’s Early Life, Education and Experiments

Galileo Galilei was born in Pisa in 1564, the first of six children of Vincenzo Galilei, a musician and scholar. In 1581 he entered the University of Pisa at age 16 to study medicine, but was soon sidetracked by mathematics. He left without finishing his degree. In 1583 he made his first important discovery, describing the rules that govern the motion of pendulums.

Did you know? After being forced during his trial to admit that the Earth was the stationary center of the universe, Galileo allegedly muttered, "Eppur si muove!" ("Yet it moves!" ). The first direct attribution of the quote to Galileo dates to 125 years after the trial, though it appears on a wall behind him in a 1634 Spanish painting commissioned by one of Galileo's friends.

From 1589 to 1610, Galileo was chair of mathematics at the universities of Pisa and then Padua. During those years he performed the experiments with falling bodies that made his most significant contribution to physics.

Galileo had three children with Marina Gamba, whom he never married: Two daughters, Virginia (Later “Sister Maria Celeste”) and Livia Galilei, and a son, Vincenzo Gamba. Despite his own later troubles with the Catholic Church, both of Galileo’s daughters became nuns in a convent near Florence.

Galileo, Telescopes and the Medici Court

In 1609 Galileo built his first telescope, improving upon a Dutch design. In January of 1610 he discovered four new “stars” orbiting Jupiter—the planet’s four largest moons. He quickly published a short treatise outlining his discoveries, “Siderius Nuncius” (“The Starry Messenger”), which also contained observations of the moon’s surface and descriptions of a multitude of new stars in the Milky Way. In an attempt to gain favor with the powerful grand duke of Tuscany, Cosimo II de Medici, he suggested Jupiter’s moons be called the “Medician Stars.”

“The Starry Messenger” made Galileo a celebrity in Italy. Cosimo II appointed him mathematician and philosopher to the Medicis , offering him a platform for proclaiming his theories and ridiculing his opponents.

Galileo’s observations contradicted the Aristotelian view of the universe, then widely accepted by both scientists and theologians. The moon’s rugged surface went against the idea of heavenly perfection, and the orbits of the Medician stars violated the geocentric notion that the heavens revolved around Earth.

Galileo Galilei’s Trial

In 1616 the Catholic Church placed Nicholas Copernicus ’s “De Revolutionibus,” the first modern scientific argument for a heliocentric (sun-centered) universe, on its index of banned books. Pope Paul V summoned Galileo to Rome and told him he could no longer support Copernicus publicly.

In 1632 Galileo published his “Dialogue Concerning the Two Chief World Systems,” which supposedly presented arguments for both sides of the heliocentrism debate. His attempt at balance fooled no one, and it especially didn’t help that his advocate for geocentrism was named “Simplicius.”

Galileo was summoned before the Roman Inquisition in 1633. At first he denied that he had advocated heliocentrism, but later he said he had only done so unintentionally. Galileo was convicted of “vehement suspicion of heresy” and under threat of torture forced to express sorrow and curse his errors.

Nearly 70 at the time of his trial, Galileo lived his last nine years under comfortable house arrest, writing a summary of his early motion experiments that became his final great scientific work. He died in Arcetri near Florence, Italy on January 8, 1642 at age 77 after suffering from heart palpitations and a fever.

What Was Galileo Famous For? 

Galileo’s laws of motion, made from his measurements that all bodies accelerate at the same rate regardless of their mass or size, paved the way for the codification of classical mechanics by Isaac Newton . Galileo’s heliocentrism (with modifications by Kepler ) soon became accepted scientific fact. His inventions, from compasses and balances to improved telescopes and microscopes, revolutionized astronomy and biology. Galilleo discovered craters and mountains on the moon, the phases of Venus, Jupiter’s moons and the stars of the Milky Way. His penchant for thoughtful and inventive experimentation pushed the scientific method toward its modern form.

In his conflict with the Church, Galileo was also largely vindicated. Enlightenment thinkers like Voltaire used tales of his trial (often in simplified and exaggerated form) to portray Galileo as a martyr for objectivity. Recent scholarship suggests Galileo’s actual trial and punishment were as much a matter of courtly intrigue and philosophical minutiae as of inherent tension between religion and science.

In 1744 Galileo’s “Dialogue” was removed from the Church’s list of banned books, and in the 20th century Popes Pius XII and John Paul II made official statements of regret for how the Church had treated Galileo.

Sign up for Inside History

Get HISTORY’s most fascinating stories delivered to your inbox three times a week.

By submitting your information, you agree to receive emails from HISTORY and A+E Networks. You can opt out at any time. You must be 16 years or older and a resident of the United States.

More details : Privacy Notice | Terms of Use | Contact Us

Galileo Galilei: Biography, inventions & other facts

Galileo revolutionized our understanding of the universe

Galileo's Experiments

Galileo's telescope, copernican system, galileo quotes.

Italian astronomer Galileo Galilei provided a number of scientific insights that laid the foundation for future scientists. His investigation of the laws of motion and improvements on the telescope helped further the understanding of the world and universe around him. Both led him to question the current belief of the time — that all things revolved around the Earth. 

[See also our overview of Famous Astronomers and great scientists from many fields who have contributed to the rich history of discoveries in astronomy .]

The Ancient Greek philosopher, Aristotle, taught that heavier objects fall faster than lighter ones, a belief still held in Galileo's lifetime. But Galileo wasn't convinced. Experimenting with balls of different sizes and weights, he rolled them down ramps with various inclinations. His experiments revealed that all of the balls boasted the same acceleration independent of their mass - although some modern physicists remain determined to prove him wrong . He also demonstrated that objects thrown in the air travel along a parabola.

At the same time, Galileo worked with pendulums. In his life, accurate timekeeping was virtually nonexistent. Galileo observed, however, that the steady motion of a pendulum could improve this. In 1602, he determined that the time it takes a pendulum to swing back and forth does not depend on the arc of the swing. Near the end of his lifetime, Galileo designed the first pendulum clock .

Galileo is often incorrectly credited with the creation of a telescope. ( Hans Lippershey applied for the first patent in 1608, but others may have beaten him to the actual invention.) Instead, he significantly improved upon them. In 1609, he first learned of the existence of the spyglass, which excited him. He began to experiment with telescope-making , going so far as to grind and polish his own lenses. His telescope allowed him to see with a magnification of eight or nine times. In comparison, spyglasses of the day only provided a magnification of three. 

It wasn't long before Galileo turned his telescope to the heavens. He was the first to see craters on the moon, he discovered sunspots, and he tracked the phases of Venus. The rings of Saturn puzzled him, appearing as lobes and vanishing when they were edge-on — but he saw them, which was more than can be said of his contemporaries. 

Of all of his telescope discoveries, he is perhaps most known for his discovery of the four most massive moons of Jupiter, now known as the Galilean moons: Io , Ganymede , Europa and Callisto . When NASA sent a mission to Jupiter in the 1990s, it was called Galileo in honor of the famed astronomer.

In his book " Sidereus Nuncius " ("Starry Messenger"), published in 1610, Galileo wrote:

"On the 7th day of January in the present year, 1610, in the first hour of the following night, when I was viewing the constellations of the heavens through a telescope, the planet Jupiter presented itself to my view, and as I had prepared for myself a very excellent instrument, I noticed a circumstance which I had never been able to notice before, namely that three little stars, small but very bright, were near the planet; and although I believed them to belong to a number of the fixed stars, yet they made me somewhat wonder, because they seemed to be arranged exactly in a straight line, parallel to the ecliptic, and to be brighter than the rest of the stars, equal to them in magnitude . . . When on January 8th, led by some fatality, I turned again to look at the same part of the heavens, I found a very different state of things, for there were three little stars all west of Jupiter, and nearer together than on the previous night."

"I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury around the Sun; which was at length established as clear as daylight by numerous other subsequent observations. These observations also established that there are not only three, but four, erratic sidereal bodies performing their revolutions around Jupiter."

Galileo may also have made the first recorded studies of the planet Neptune, though he didn't recognize it as a planet. While observing Jupiter's moons in 1612 and 1613, he recorded a nearby star whose position is not found in any modern catalogues.

"It has been known for several decades that this unknown star was actually the planet Neptune," University of Melbourne physicist David Jamieson told Space.com . "Computer simulations show the precision of his observations revealing that Neptune would have looked just like a faint star almost exactly where Galileo observed it."

In Galileo's lifetime, all celestial bodies were thought to orbit the Earth. Supported by the Catholic Church, teaching opposite of this system was declared heresy in 1615.

Galileo, however, did not agree. His research — including his observations of the phases of Venus and the fact that Jupiter boasted moons that didn't orbit Earth — supported the Copernican system, which (correctly) stated that the Earth and other planets circle the sun.

In 1616, he was summoned to Rome and warned not to teach or write about this controversial theory. But in 1632, believing that he could write on the subject if he treated it as a mathematical proposition, he published work on the Copernican system. He was found guilty of heresy , and was placed under house arrest for the remaining nine years of his life.

Today, Galileo is finally recognized for his groundbreaking discoveries, for which he is remembered as the "father of modern science".

Related: 'Galileo Project' will search for evidence of extraterrestrial life from the technology it leaves behind

"And yet it moves."

"I have never met a man so ignorant that I couldn't learn something from him."

"I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use."

"You cannot teach a man anything, you can only help him find it within himself."

"It is a beautiful and delightful sight to behold the body of the Moon."

"Wine is sunlight, held together by water."

— Find other quotes at GoodReads.com .

Additional resources

• Rice University: The Galileo Project
• JPL: Galileo Mission to Jupiter
• Stanford University Solar Center: Galileo’s Discoveries

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Get the Space.com Newsletter

Breaking space news, the latest updates on rocket launches, skywatching events and more!

Nola Taylor Tillman is a contributing writer for Space.com. She loves all things space and astronomy-related, and enjoys the opportunity to learn more. She has a Bachelor’s degree in English and Astrophysics from Agnes Scott college and served as an intern at Sky & Telescope magazine. In her free time, she homeschools her four children. Follow her on Twitter at @NolaTRedd

China launches Chang'e 6 sample-return mission to moon's far side (video)

A Switzerland-size hole opened in Antarctica's sea ice in 2016-17. Now we know why

See the sun's corona revealed in all its glory during 2024 total solar eclipse (photo)

Most Popular

• 2 See this galaxy's bright center? It's home to a voracious supermassive black hole
• 3 Black hole collision 'alerts' could notify astronomers within 30 seconds of detection
• 4 New moon of May 2024 tonight welcomes the stars of summer
• 5 Should we seal DNA samples of Earth's endangered species in a moon crater?

Advertisement

Supported by

Starry Messenger

• Share full article

By Owen Gingerich

• Dec. 24, 2010

Galileo Galilei, “martyr of science” in the picturesque 19th-­century expression, has undoubtedly attracted more biographers than Copernicus, Kepler, Newton and Einstein combined. His run-in with the Roman Catholic Church over the motion of the earth, his forced confession and his famous stage-­whispered riposte — “ e pur si muove,” “but yet it moves” (which surely was never delivered) — are all the makings of high drama.

So thought Bertolt Brecht, who wrote his play “Galileo” three times. The first time, in 1938, he portrayed the scientist as hero. His remake, after the trauma of Hiroshima and Nagasaki, pictured Galileo as a tool of the state. And the final, Marxist-tinged version, written in 1953, after Brecht returned to East Berlin from America, showed the artist as tool of the state — telling us perhaps more about Brecht than about Galileo.

Inevitably, the serious biographer also mirrors something of himself in depicting his subject. Readers who make it through the occasional eye-glazing geometrical digression in J. L. Heilbron’s “Galileo” will not be surprised to find that the author’s extensive output includes a fresh explication of Euclid. Likewise, the reader of David Wootton’s “Galileo: Watcher of the Skies,” which includes a revisionist chapter on Galileo’s “(un)belief,” as he puts it, will not be surprised to learn that Wootton has written repeatedly about atheism.

Each of these books demonstrates an awesome command of the vast Galileo literature. Heilbron, an emeritus professor of the history of science at Berkeley, is more fine-grained in his approach, leavening his account with wit and irony. Wootton, a historian at the University of York, excels in boldly speculating about Galileo’s motives and the overall trajectory of his life, seeking to understand why Galileo cared so much about Copernicus’s heliocentric view of the heavens.

The Galileo story is full of puzzles. In 1597 he wrote to Kepler that he was essentially a closet Copernican, with unspecified new arguments in support of the idea that the earth moved around the sun. But he never responded to Kepler’s urging that he stand forth in his opinions. Instead, Galileo continued to teach the ancient geocentric view, while making remarkable progress in studying the motion of falling bodies. Until age 46 he had published nothing remarkable. Then, in 1610, he burst onto the international stage with “The Starry Messenger,” announcing his discovery, via telescope, of the craters and mountains on the moon, the four bright moons of Jupiter and the fact that the Milky Way is composed of millions of distinct stars. Thereafter followed his discovery of the phases of Venus — which proved that it had to revolve around the sun, not the earth — and of sunspots.

By 1615 Galileo’s career of scientific discovery was essentially finished, although some of his most influential work still remained unpublished. “The Starry Messenger” had served as a successful job application for a position in the Medici court in Florence. His friends in the Venetian Republic were disappointed and even outraged at his decision to leave the intellectually freer atmosphere of Padua and Venice for Tuscany, which was under the Vatican’s thumb. Wootton argues that Galileo had a particularly ambitious goal: to persuade the Roman hierarchy to leave open the cosmological choice between the Aristotelian geocentrism and Copernicus’s heliocentrism; and that this could be more easily done from Florence. While Galileo was comparatively indifferent to the salary offered, he insisted that his title include the word “philosopher.” He wanted to be a philosopher credentialed to say how the world was really made, not just a mathematician able to validate a hypothetical scheme for computing the position of planets.

In both biographies Galileo emerges as an ambiguous hero-antihero. Wootton explains right at the beginning how the surviving documentation has long been winnowed and spun by friends and scholars eager to paint Galileo as a good Catholic. His own spin is that for Galileo, cosmology was paramount over theology and Copernicism proved “the fundamental insignificance of the human species.” But the idea of human insignificance belongs to our time, not Galileo’s.

Heilbron, on the other hand, makes no big issue of any religious unorthodoxies on Galileo’s part beyond his Copernicism, though surely there must have been some. Unlike Wootton, he doesn’t see any secret unbelief underneath the public Catholicism, noting in passing that when Galileo, near the end of his life, was under a strict house arrest on charges of heresy, Urban VIII granted him special permission to attend Mass at a nearby church.

Everyone agrees that Galileo was an incorrigible egotist, so full of himself that he repeatedly misjudged his ability to persuade the authorities of his own opinions. His attempt via the Jesuit astronomers in 1615-16 to convince the Vatican backfired and, in Wootton’s view, led to an increasing estrangement with the Jesuits. Both Wootton and Heilbron are sharply critical of Galileo’s unnecessary alienation of the Jesuits, and Heilbron in particular highlights Galileo’s scientific fumbles, both in the debates with the Jesuits and later in his controversial “Dialogue on the Two Chief World Systems” (1632). As he wryly comments, “It was not Galileo’s style to accept corrections from others.”

The “Dialogue” was ostensibly a neutral comparison of the geocentric and Copernican cosmologies, but Galileo could not help giving pride of place to the heliocentric arrangement. He had been warned not to hold or teach the Copernican system, so inevitably he got himself into deep trouble with the Inquisition. He was ordered to Rome to stand trial and placed under house arrest for the remainder of his life. The “Dialogue” was in fact not a great classic of scientific discovery. It was, however, the book that won the war, the persuasive account that made the Copernican cosmology intellectually respectable. Ironically, it is Galileo’s ­lesser-known “Discourses on Two New Sciences” (1638) that stands as his greatest scientific contribution and a forerunner to Newton’s powerful physics. A major part of that work had already been prepared in Padua before the telescope propelled Galileo to international fame.

For the general reader, Wootton’s is likely to be the more engaging account; Heilbron’s, though, has much richer scientific detail, and will no doubt become the standard, comprehensive biography. Early in the book, Heilbron has a serious mathematical discussion of Galileo’s Paduan period. In one of his most inventive sections, he creates a Galilean dialogue on issues of algebra and geometry. Though not easy to read, it brilliantly expresses the ambiguities and blind alleys as Galileo wrestled with the conceptual difficulty of introducing a non-geometrical quantity — time itself — into the proportions. These issues did not find their final formulation until the end of his life, when he raced to complete “Two New Sciences” and smuggle it to Holland for publication.

Galileo was the most articulate spokesman for the new astronomy, the pioneer who set observational astronomy on its modern track. He simply had the misfortune to be born in the period when the Reformation, the Counter-Reformation and the Thirty Years’ War greatly restricted his intellectual options.

Watcher of the Skies

By David Wootton

Illustrated. 328 pp. Yale University Press. $35.

By J. L. Heilbron

Illustrated. 508 pp. Oxford University Press. $34.95.

Owen Gingerich is an emeritus professor of astronomy and the history of science at the Harvard-Smithsonian Center for Astrophysics.

Explore More in Books

Want to know about the best books to read and the latest news start here..

The complicated, generous life  of Paul Auster, who died on April 30 , yielded a body of work of staggering scope and variety .

“Real Americans,” a new novel by Rachel Khong , follows three generations of Chinese Americans as they all fight for self-determination in their own way .

“The Chocolate War,” published 50 years ago, became one of the most challenged books in the United States. Its author, Robert Cormier, spent years fighting attempts to ban it .

Joan Didion’s distinctive prose and sharp eye were tuned to an outsider’s frequency, telling us about ourselves in essays that are almost reflexively skeptical. Here are her essential works .

Each week, top authors and critics join the Book Review’s podcast to talk about the latest news in the literary world. Listen here .

Galileo Galilei discovered that the Earth orbits the sun, an observation for which he was put under house arrest for the last eight years of his life.

Galileo Matters More Than Ever on His 450th Birthday

The scientist's insights continue to enrich our world.

Not every astronomer can claim to have enjoyed both the attention of the Inquisition and the Indigo Girls , but then again, Galileo was no ordinary genius.

Discoverer of moons, toppler of Aristotle's physics, and celebrated loser of history's most famous heresy trial, Galileo Galilei's greatest invention, in truth, was our own modern world.

On the 450th anniversary of his birth today, February 15, 2014, it's worth taking a telescopic look at the achievements of this unparalleled genius of the Renaissance. Born in 1564 in Pisa, Italy, Galileo lived to the age of 77 , a life span that saw the start of the scientific revolution in Europe. (See also: " Galileo's Telescope at 400 .")

For Hungry Minds

Galileo is still in the news. An optical illusion he discovered in the 1600s caused Venus to appear much larger and blurrier—a "radiant crown," as Galileo called it—when seen through a telescope than when viewed with the naked eye.

The puzzle was finally understood just this week. Neuroscientists from the State University of New York College of Optometry report that the answer lies in the wiring of our visual brain cells . The brain responds to light and dark objects differently, so the brightness of a planet distorts its apparent size when it is seen against the dark background of space.

Heaven and Hell

"Infinite thanks to God," Galileo wrote in 1610, "for being so kind as to make me alone the first observer of marvels kept hidden."

He was celebrating his discovery of Jupiter's four large moons : Io, Europa, Ganymede, and Callisto. Originally he wanted to name the moons after his noble patrons, four brothers of Florence's famed Medici family called Cosimo, Francesco, Carl, and Lorenzo. Other astronomers, perhaps thankfully, assigned more elevated names to the moons, ones taken from mythology for the consorts of Jupiter, king of the gods.

Those moons revealed that some objects revolved around something other than the Earth, which helped Galileo to discover heliocentrism, or the fact that the Earth circles the sun. This finding, in turn, would earn him the attention of the Inquisition, which investigated religious rebellion and heresy in the world of 16th-century Italy. The Vatican officially apologized in 2000 for Galileo's heresy trial, which resulted in the scientist being kept under house arrest for the last eight years of his life.

Using telescopes he built, Galileo was the first to identify the four large moons of Jupiter.

Cannonball Physics

Galileo's most famous experiment, which he likely never really performed, was the 1589 dropping of cannonballs with different masses off the Leaning Tower of Pisa . The goal of this experiment was to show that objects fall at a uniform rate, that gravity doesn't make heavier objects fall faster.

That notion was contrary to classic Greek physics, which held that heavier objects fall faster . In 1971 the experiment was repeated on the moon (to remove the effects of air resistance) by Apollo 15 astronauts , who dropped a hammer and a feather to confirm Galileo's observation.

What was notable about the experiment was precisely that it was an experiment. Earlier models of scientific inquiry were reasoned entirely in the mind or argued from theological principles. Galileo, by contrast, advanced the fundamental idea that science relied on experiments to prove its contentions. This simple idea—prove it—was radical at the time.

You May Also Like

Does this ‘secret room’ contain Michelangelo’s lost artwork? See for yourself.

The window into Leonardo da Vinci's creativity? His sketchbooks

A surprising must-wear for European monarchs? Weasels.

Galileo went even further, pioneering the idea that mathematics are essential to scientific observations, and abjuring the literary hand-waving of ancient texts. He was the father of mathematical physics, reporting his observations in tables that inspired today's lab books. The diagrams he made depicting astronomical objects are clear forerunners to modern ones.

He put his knowledge to practical use, grinding the lenses for improved telescopes that allowed him to make astronomical discoveries ahead of other scholars—spotting moons, finding sunspots, and peering into the craters of Earth's moon.

As recounted in his volume Starry Messenger , Galileo crafted a telescope for the sailing masters of Venice that magnified views by at least eight times, helping them look out for pirates on trading voyages.

According to legend, Galileo dropped a cannonball and a wooden ball from the Leaning Tower of Pisa to see which fell faster.

Open Access Science

In his writings and books, some published in Holland to avoid the wrath of the Inquisition, Galileo gave shape to an ideal that exists in the scientific community to this very day: that scientists are united in their quest to understand the unknown and that their voyage of discovery transcends national borders. Galileo widely corresponded with other natural philosophers and the great innovative minds of his time, such as Johannes Kepler , who first wrote down the laws of orbital motion.

In writing down their discoveries, Galileo and his contemporaries created the beginnings of the system of scientific correspondence that we know today as scientific journals, where discoveries are openly described by their methods, results, and possible shortfalls.

This was quite a contrast to the gnomic writings of alchemists, who cloaked their recipes in mythological allusions and double-talk. The open discourse of the scientific enterprise is one of the abiding gifts of the Renaissance. (Although it is worth noting that Galileo resorted to scrambling news of his findings in code in letters to Kepler.)

Galileo not only wrote to fellow scholars, he also wrote for the public, notes historian Doug Linder in his account of the trial of Galileo . "He seemed compelled to act as a consultant in natural philosophy to all who would listen," Linder writes. "He wrote in tracts, pamphlets, letters, and dialogues—not in the turgid, polysyllabic manner of a university pedant, but simply and directly."

That talent for communication was quite likely what got him in hot water with religious authorities, ending with the heresy trial, one of history's crueler attacks on independent thinking. The trial haunted the Vatican for centuries; its treatment of Galileo added momentum to the Enlightenment's demand for intellectual freedom, which opened the way for such documents as the U.S. Constitution and the United Nations Universal Declaration of Human Rights .

The scientist's communication skills were said to be overbearing at times. "Everyone agrees that Galileo was an incorrigible egotist, so full of himself that he repeatedly misjudged his ability to persuade the authorities of his own opinions," astronomical historian Owen Gingerich of the Harvard-Smithsonian Center for Astrophysics noted in a recent review of Galileo biographies .

Whatever his flaws, "Galileo was the most articulate spokesman for the new astronomy, the pioneer who set observational astronomy on its modern track," Gingerich said.

And beyond his scientific achievements, Galileo is remembered in the popular imagination as a courageous truthseeker, a view expressed in the song "Galileo" by the folk rock group Indigo Girls. He was, they sing, "king of night vision, king of insight."

Remembered, too, 450 years after his birth, is Galileo's (likely apocryphal) rejoinder to the Inquisitors, " Yet still, it moves ." He was talking about the Earth, which today everyone knows as one of many planets, a place happily shaped more by Galileo than by any of his persecutors.

Follow Dan Vergano on Twitter .

Related Topics

• RENAISSANCE
• ANIMAL REPRODUCTION

This 16th-century map is teeming with sea monsters. Most are based on a real mammal.

Beards and mustaches have a weirder history than you think

What's inside Leonardo da Vinci's notebooks?

Dante's 'Inferno' is a journey to hell and back

Dog DNA tests are on the rise—but are they reliable?

• Environment

History & Culture

• History & Culture
• History Magazine
• Mind, Body, Wonder
• Coronavirus Coverage
• Paid Content
• Terms of Use
• Privacy Policy
• Your US State Privacy Rights
• Children's Online Privacy Policy
• Interest-Based Ads
• About Nielsen Measurement
• Do Not Sell or Share My Personal Information
• Nat Geo Home
• Attend a Live Event
• Book a Trip
• Inspire Your Kids
• Shop Nat Geo
• Visit the D.C. Museum
• Learn About Our Impact
• Support Our Mission
• Advertise With Us
• Customer Service
• Renew Subscription
• Manage Your Subscription
• Work at Nat Geo
• Sign Up for Our Newsletters
• Contribute to Protect the Planet

Copyright © 1996-2015 National Geographic Society Copyright © 2015-2024 National Geographic Partners, LLC. All rights reserved

Biography Online

Galileo Galilei Biography

Short biography of Galileo

Galileo was born in Pisa, Duchy of Florence, Italy in 1564 to a poor but noble family.

His parents recognised their child’s innate intelligence and talents and made sacrifices to have him educated. At his father’s insistence, Galileo studied the profitable career of medicine. But, at the University of Pisa, Galileo became fascinated by a wide range of subjects. He also became critical of many of Aristotle ‘s teaching which had dominated education for the past 2,000 years.

Galileo was appointed to be a mathematics professor at the University of Pisa, but his strident criticisms of Aristotle left him isolated amongst his contemporaries. After three years of persecution, he resigned and went to the University of Padua, where he taught maths. His entertaining lectures attracted a large following, and he was able to spend the next 18 years pursuing his interests in astronomy and mechanics.

During this time, Galileo made important discoveries about gravity, inertia and also developed the forerunner of the thermometer. He also worked on the pendulum clock Galileo also worked tirelessly on the science of gnomonics (telling time by shadows) and the laws of motion.

It was in astronomy that Galileo became most famous. In particular, his support for heliocentrism garnered the opposition of the Holy Roman Catholic Church.

Galileo came to the same conclusions of Copernicus – that the sun was the centre of the universe and not the earth. Galileo was also a great admirer of Johannes Kepler for his work on planetary motions.

By inventing the world’s first powerful telescope, Galileo was able to make many ground-breaking explorations of the universe. Galileo’s His telescopes increased magnification from around just 2x to around 30x magnification. Using this new telescope he found that:

• Saturn had a beautiful ring of clouds.
• The moon was not flat but had mountains and craters.
• Using his own telescope, he discovered four moons of Jupiter – Io, Ganymede, Callisto, and Europa. He also noted these moons revolved around Jupiter rather than the sun.

To support the theory of heliocentrism, Galileo had the mathematical proofs of Copernicus but also new proofs from the science of astronomy. However, Galileo knew that publishing these studies would bring the disapproval of the church authorities. Yet, he also felt a willingness to risk the church’s displeasure.

“I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use.”

—Galileo Galilei, Letter to the Grand Duchess Christina

Galileo was a devout Catholic. He had considered the priesthood as a young man. However, he felt the church was mistaken to take the Bible as a literal source for all scientific studies. As Galileo stated: “The Bible shows the way to go to heaven, not the way the heavens go.” The church’s opposition to heliocentrism centred on Biblical sentences, such as “the world is firmly established, it cannot be moved.” 1 Chronicles 16:30. Galileo contended this was a mistaken view of faith and the Bible.

“Copernicus never discusses matters of religion or faith, nor does he use argument that depend in any way upon the authority of sacred writings which he might have interpreted erroneously. … He did not ignore the Bible, but he knew very well that if his doctrine were proved, then it could not contradict the Scriptures when they were rightly understood.”

Letter to the Grand Duchess Christina (1615)

The Church had already started to forbid Galileo’s teachings, especially anything that supported Copernicus. However, in 1623, a new pope, Pope Urban VIII seemed to be more liberally minded, and he allowed Galileo to publish his great works on astronomy – supporting the ideas of Copernicus.

However, after the publication of Dialogue Concerning the Two Chief World Systems , conservative elements within the Church sought to attack Galileo’s beliefs and writings. In this pamphlet, Galileo appeared to ridicule the words of Pope Urban VIII – making the Pope less sympathetic to Galileo. As a consequence, Galileo was arrested and imprisoned for several months. He was convicted of heresy and was forced to recant his beliefs.  One apocryphal story relates to how Galileo, after recanting his scientific beliefs, muttered under his breath – the rebellious phrase:

“ And yet it moves .”

He spent the remaining years of his life under house arrest at Arceti.

Galileo had three children, born out of wedlock to Marina Gamba. He was especially close to one of his daughters, Polissena; she took the name of Sister Maria Celeste and entered a convent near Arceti.

Despite being censured by the church, Galileo continued to make discoveries until death overtook him in 1642. Under house arrest, he was able to write Two New Sciences ; this summarised his earlier work on the new sciences now called kinematics and the strength of materials. One of Galileo’s significant contributions to the Scientific Revolution was to depict the laws of nature in mathematical terms but also to make an effective use of experiment and observation to develop theories.

“Philosophy is written in that great book which ever lies before our eyes — I mean the universe — but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written. This book is written in the mathematical language.”

– Galileo, Il Saggiatore (1623)

His law “A body moving on a level surface will continue in the same direction at constant speed unless disturbed.” was incorporated into Sir Isaac Newton’s laws of motion His influential work led many to call him the father of ‘Modern Physics.’ Albert Einstein would later pay tribute to the contributions of Galileo.

“ In advocating and fighting for the Copernican theory Galileo was not only motivated by a striving to simplify the representation of the celestial motions. His aim was to substitute for a petrified and barren system of ideas the unbiased and strenuous quest for a deeper and more consistent comprehension of the physical and astronomical facts. ”

Foreword, written by Einstein, to a 2001 edition of Galileo’s famous book Dialogue Concerning the Two Chief World Systems.

Galileo was blind by the time he passed away on 8 January 1642, aged 77.

Citation: Pettinger, Tejvan . “ Biography of Galileo Galilei” , Oxford, UK  www.biographyonline.net 23rd July 2011. Last updated 17th March 2018.

Galileo at Amazon

Related pages

Other pages

• Inventions that changed the world
• Greatest Italians

How Galileo Changed Your Life

Galileo developed one of the first telescopes

Galileo didn’t invent the telescope — it was invented by Dutch eyeglass makers — but he made significant improvements to it. After learning about the Dutch invention, he was able to develop one of his own, teaching himself how to ground lenses. His first version magnified distant objects by three times. By that fall, he could produce lenses with a 20x magnification.

His innovations brought him both professional and financial success. He was given a lifetime tenure position at the University of Padua, where he had been teaching for several years, at double his salary. And he received a contract to produce his telescopes for a group of Venetian merchants, eager to use them as a navigational tool.

He helped created modern astronomy

Galileo turned his new, high-powered telescope to the sky. In early 1610, he made the first in a remarkable series of discoveries. He spent several weeks observing a set of stars near Jupiter as they revolved around the planet. He had discovered Jupiter’s four moons, which he named the Medicean Stars (after his patrons, the powerful Medici family), but which have since been renamed the Galilean moons, in his honor. Galileo’s close study of orbits of Jupiter’s moons and their eclipses helped create more accurate time table and measurements that later mapmakers built upon for the practice of cartography.

While the scientific doctrine of the day held that space was perfect, unchanging environments created by God, Galileo’s telescope helped change that view. His studies and drawings showed the Moon had a rough, uneven surface that was pockmarked in some places, and was actually an imperfect sphere. Galileo also observed the phases of planet Venus and the existence of far more stars in the Milky Way that weren't visible to the naked eye.

He was also one of the first people to observe the phenomena known as sunspots, thanks to his telescope which allowed him to view the sun for extended periods of time without damaging the eye. This discovery also saw one of his first scientific clashes, as he used his evidence to debate fellow scientists who argued that the sunspots were actually satellites of the sun and not irregularities.

Galileo helped prove that the Earth revolved around the sun

In 1610, Galileo published his new findings in the book Sidereus Nuncius , or Starry Messenger , which was an instant success. The Medicis helped secure him an appointment as a mathematician and philosopher in his native Tuscany.

He became close with a number of other leading scientists, including Johannes Kepler. A German astronomer and mathematician, Kepler’s work helped lay the foundations for the later discoveries of Isaac Newton and others.

Kepler’s experiments had led him to support the idea that the planets, Earth included, revolved around the sun. This heliocentric theory, as well as the idea of Earth’s daily rotational turning, had been developed by Polish astronomer Nicolaus Copernicus half a century earlier. Galileo and Kepler exchanged correspondence around Kepler’s ideas of planetary motion, and their detailed studies and observations helped spur the Scientific Revolution.

Their belief that the Sun, and not the Earth, was the gravitational center of the universe, upended almost 2,000 years of scientific thinking, dating back to theories about the fixed, unchanging universe put forth by the Greek philosopher and scientist Aristotle . Galileo had been testing Aristotle’s theories for years, including an experiment in the late 16th century in which he dropped two items of different masses from the Leaning Tower of Pisa, disproving Aristotle’s belief that objects would fall at differing speeds based on their weight (Newton later improved upon this work).

Galileo paid a high price for his contributions

But challenging the Aristotelian or Ptolemaic theories about the Earth’s role in the universe was dangerous stuff. Geocentrism was, in part, a theoretical underpinning of the Roman Catholic Church. Galileo’s work brought him to the attention of Church authorities, and in 1615, he was called before the Roman Inquisition, accused of heresy for beliefs which contradicted Catholic scripture. The following year, the Church banned all works that supported Copernicus’ theories and forbade Galileo from publicly discussing his works.

Galileo kept quiet for more than 15 years, during which he quietly continued his experiments. In 1632, after the election of a new pope who he considered more liberal, he published another book, Dialogue on the Two Chief World Systems, Ptolemaic and Copernican , which argued both sides of the scientific (and religious) debate but fell squarely on the side of Copernicus’ heliocentrism. Galileo was once again summoned to Rome. In 1633, following a trial, he was found guilty of suspected heresy, forced to recant his views and sentenced to house arrest until his death in 1642.

It took nearly 200 years after Galileo’s death for the Catholic Church to drop its opposition to heliocentrism. In 1992, after a decade-long process and 359 years after his heresy conviction, Pope John Paul II formally expressed the Church’s regret over Galileo’s treatment. In 1995, an unmanned NASA spacecraft named Galileo landed on Jupiter to begin a multi-year study of the planet and its moons, which Galileo had helped identify in 1610.

SIGN UP FOR THE BIOGRAPHY.COM NEWSLETTER

Famous Mathematicians

Archimedes: The Mathematician Who Discovered Pi

Benjamin Banneker

22 Famous Scientists You Should Know

Charles Babbage

Blaise Pascal

Leonhard Euler

Ada Lovelace

Valerie Thomas

Mary Jackson

Books About and By Galileo Galilei

• Important Astronomers
• An Introduction to Astronomy
• Solar System
• Stars, Planets, and Galaxies
• Space Exploration
• Weather & Climate

From Genius to Heretic and Back Again.

Galileo Galilei  is well-known for his astronomical discoveries and as one of the first people to use a telescope to look at the sky. He is often referred to as one of the "fathers" of modern astronomy. Galileo had a turbulent and interesting life, and clashed often with the church (which didn't always approve of his work). Most people know of his first observations of the  gas giant planet Jupiter , and his discovery of the rings of  Saturn . But, Galileo also studied the  Sun  and stars. 

Galileo was the son of a famous musician and music theorist named  Vincenzo Galileo  (who was himself a rebel, but in musical circles). The younger Galileo was educated at home and then by monks at Vallombrosa. As a young man, he entered the University of Pisa in 1581 to study medicine. There, he found his interests changing to philosophy and mathematics and he ended his university career in 1585 without a degree.

in the early 1600s, Galileo  constructed his own telescope  based on a design he saw by optics expert Hans Lippershey . Using it to observe the sky, he began to write extensively about it and his theories about the objects he saw in it. His work caught the attention of church elders, and in later years he was accused of blasphemy when his observations and theories contradicted official teachings about the Sun and planets.

Galileo wrote several works that are still studied today, particularly students of astronomy history and those interested in the Renaissance during which he lived. In addition, Galileo's life and accomplishments continually attract writers interested in exploring those topics further for general audiences. The following list comprises some of his own work, plus expert insights into his life by more modern writers.

Read Galileo's Work and Works about Him

Discoveries and Opinions of Galileo,   by Galileo Galilei. Translated by Stillman Drake. Straight from the horse's mouth, as the saying goes. This book is a translation of some of Galileo's writings and provides great insight into his thoughts and ideas. He spent much of his adult life observing the heavens and making notes of what he saw. Those notes are encapsulated in his writings.

Galileo, by Bertolt Brecht. An unusual entry on this list. It's actually a play, originally written in German, about the life of Galileo. Brecht was a German playwright who lived and worked in Munich, Bavaria.

Galileo's Daughter,  by Dava Sobel. This is a fascinating look at Galileo's life as seen in letters to and from his daughter. Although Galileo never married, he had a short relationship with a woman named Marina Gamba. She actually bore him three children and lived in Venice.

Galileo Galilei: Inventor, Astronomer, and Rebel,  by Michael White. This is a more recent biography of Galileo.

Galileo in Rome,  by Mariano Artigas. Everyone is fascinated by Galileo's trial before the Inquisition. This book tells of his various trips to Rome, from his younger days through his famous trial. It was hard to put down.

Galileo's Pendulum,  by Roger G. Newton. I found this book to be an intriguing look at a young Galileo and one of the discoveries which led to his place in scientific history.

The Cambridge Companion to Galileo,  by Peter K. Machamer. This book is an easy read for just about anyone. Not a single story, but a series of essays that delve into Galileo's life and work, and is a useful reference book on the man and his work.

The Day the Universe Changed,   by James Burke, who looks at Galileon's life and his influence on history.

The Eye of the Lynx : Galileo, His Friends, and the Beginnings of Modern Natural,  by David Freedberg. Galileo belonged to the secretive Linxean society, a group of scholarly individuals. This book describes the group and especially their most famous member and his contributions to modern science and natural history.

Starry Messenger.   Galileo's own words, illustrated by wonderful images. This is a must for any library. (translated by Peter Sis). Its original name is Sidereus Nuncius, and was published in 1610. It decribes his work on telescopes, and his subsequent observations of the Moon, Jupiter, and other celestial objects.

Edited and updated by  Carolyn Collins Petersen.

• Biography of Galileo Galilei, Renaissance Philosopher and Inventor
• The Inventions of Galileo Galilei
• Galileo Galilei Quotes
• What Is Astronomy and Who Does It?
• Journey Through the Solar System: Planets, Moons, Rings and More
• Journey Through the Solar System: Planet Jupiter
• A Short History of the Scientific Revolution
• Who Invented the Telescope?
• Hans Lippershey: Telescope and Microscope Inventor
• Saturn: Sixth Planet from the Sun
• Biography of Antonie van Leeuwenhoek, Father of Microbiology
• The History of the Telescope and Binoculars
• Percival Lowell: Astronomer Who Searched for Life on Mars
• Meet William Herschel: Astronomer and Musician
• Explore Johannes Kepler's Laws of Motion
• Journey Through the Solar System: Saturn

• Table of Contents
• New in this Archive
• Chronological
• Editorial Information
• About the SEP
• Editorial Board
• How to Cite the SEP
• Special Characters
• Support the SEP
• PDFs for SEP Friends
• Make a Donation
• SEPIA for Libraries
• Entry Contents

Bibliography

Academic tools.

• Friends PDF Preview
• Author and Citation Info
• Back to Top

Galileo Galilei

Galileo Galilei (1564–1642) has always played a key role in any history of science and, in many histories of philosophy, he is a, if not the, central figure of the scientific revolution of the 17 th Century. His work in physics or natural philosophy, astronomy, and the methodology of science still evoke debate after over 400 years. His role in promoting the Copernican theory and his travails and trials with the Roman Church are stories that still require re-telling. This article attempts to provide an overview of these aspects of Galileo’s life and work, but does so by focusing in a new way on his arguments concerning the nature of matter.

1. Brief Biography

2. introduction and background, 3. galileo’s scientific story, 4. galileo and the church, other internet resources, related entries.

Galileo was born on February 15, 1564 in Pisa. By the time he died on January 8, 1642 (but see problems with the date, Machamer 1998, pp. 24–5) he was as famous as any person in Europe. Moreover, when he was born there was no such thing as ‘science’, yet by the time he died science was well on its way to becoming a discipline and its concepts and method a whole philosophical system.

Galileo and his family moved to Florence in 1572. He started to study for the priesthood, but left and enrolled for a medical degree at the University of Pisa. He never completed this degree, but instead studied mathematics notably with Ostilio Ricci, the mathematician of the Tuscan court. Later he visited the mathematician Christopher Clavius in Rome and started a correspondence with Guildobaldo del Monte. He applied and was turned down for a position in Bologna, but a few years later in 1589, with the help of Clavius and del Monte, he was appointed to the chair of mathematics in Pisa.

In 1592 he was appointed, at a much higher salary, to the position of mathematician at the University of Padua. While in Padua he met Marina Gamba, and in 1600 their daughter Virginia was born. In 1601 they had another daughter Livia, and in 1606 a son Vincenzo.

It was during his Paduan period that Galileo worked out much of his mechanics and began his work with the telescope. In 1610 he published The Starry Messenger , and soon after accepted a position as Mathematician,a non-teaching post at University of Pisa and Philosopher to the Grand Duke of Tuscany. A facsimile copy of The Library of Congress’ manuscript of The Starry Messenger and a symposium discussing details about the manuscript, may be found in Hessler and DeSimone 2013. Galileo had lobbied hard for this position at the Medici court and even named the moons of Jupiter, which he discovered, after the Medici. There were many reasons hewanted move, but he says he did not like the wine in the Venice area and he had to teach too many students. Late in 1610, the Collegio Romano in Rome, where Clavius taught, certified the results of Galileo’s telescopic observations. In 1611 he became a member of what is perhaps the first scientific society, the Academia dei Lincei.

In 1612 Galileo published a Discourse on Floating Bodies , and in 1613, Letters on the Sunspots . In this latter work he first expressed his position in favor of Copernicus. In 1614 both his daughters entered the Franciscan convent of Saint Mathew, near Florence. Virginia became Sister Maria Celeste and Livia, Sister Arcangela. Marina Gamba, their mother, had been left behind in Padua when Galileo moved to Florence.

In 1613–4 Galileo entered into discussions of Copernicanism through his student Benedetto Castelli, and wrote a Letter to Castelli . In 1616 he transformed this into the Letter to the Grand Duchess Christina . In February 1616, the Sacred Congregation of the Index condemned Copernicus’ book On the Revolution of the Heavenly Orbs , pending correction. Galileo then was called to an audience with Cardinal Robert Bellarmine and advised not to teach or defend Copernican theory.

In 1623 Galileo published The Assayer dealing with the comets and arguing they were sublunary phenomena. In this book, he made some of his most famous methodological pronouncements including the claim the book of nature is written in the language of mathematics.

The same year Maffeo Barberini, Galileo’s supporter and friend, was elected Pope Urban VIII. Galileo felt empowered to begin work on his Dialogues concerning the Two Great World Systems . It was published with an imprimatur from Florence (and not Rome) in 1632. Shortly afterwards the Inquisition banned its sale, and Galileo was ordered to Rome for trial. In 1633 he was condemned. There is more about these events and their implications in the final section of this article, Galileo and the Church .

In 1634, while Galileo was under house arrest, his daughter, Maria Celeste died (cf. Sobel 1999). At this time he began work on his final book, Discourses and Mathematical Demonstrations concerning Two New Sciences . This book was smuggled out of Italy and published in Holland. Galileo died early in 1642. Due to his conviction, he was buried obscurely until 1737.

For detailed biographical material, the best and classic work dealing with Galileo’s life and scientific achievements is Stillman Drake’s Galileo at Work (1978). More recently, J.L. Heilbron has written a magnificent biography, Galileo , that touches on all the multiple facets of Galileo’s life (2010). A strange popularization based somewhat on Heilbron’s book, by Adam Gopik, appeared in The New Yorker in 2013.

For many people, in the Seventeenth Century as well as today, Galileo was and is seen as the ‘hero’ of modern science. Galileo discovered many things: with his telescope, he first saw the moons of Jupiter and the mountains on the Moon; he determined the parabolic path of projectiles and calculated the law of free fall on the basis of experiment. He is known for defending and making popular the Copernican system, using the telescope to examine the heavens, inventing the microscope, dropping stones from towers and masts, playing with pendula and clocks, being the first ‘real’ experimental scientist, advocating the relativity of motion, and creating a mathematical physics. His major claim to fame probably comes from his trial by the Catholic Inquisition and his purported role as heroic rational, modern man in the subsequent history of the ‘warfare’ between science and religion. This is no small set of accomplishments for one 17 th -century Italian, who was the son of a court musician and who left the University of Pisa without a degree.

One of the good things about dealing with such momentous times and people is that they are full of interpretive fecundity. Galileo and his work provide one such occasion. Since his death in 1642, Galileo has been the subject of manifold interpretations and much controversy. The use of Galileo’s work and the invocations of his name make a fascinating history (Segre 1991, Palmerino and Thijssen 2004,  Finocchiaro 2005), but this is not our topic here.

Philosophically, Galileo has been used to exemplify many different themes, usually as a side bar to what the particular writer wished to make the hallmark of the scientific revolution or the nature of good science. Whatever was good about the new science or science in general, it was Galileo who started it. One early 20th Century tradition of Galileo scholarship used to divvy up Galileo’s work into three or four parts: (1) his physics, (2) his astronomy, and (3) his methodology, which could include his method of Biblical interpretation and his thoughts about the nature of proof or demonstration. In this tradition, typical treatments dealt with his physical and astronomical discoveries and their background and/or who were Galileo’s predecessors. More philosophically, many would ask how his mathematics relates to his natural philosophy? How did he produce a telescope and use his telescopic observations to provide evidence in favor of Copernicanism (Reeves 2008)? Was he an experimentalist (Settle 1961, 196, 1983, 1992; Palmieri 2008), a mathematical Platonist (Koyré 1939), an Aristotelian emphasizing experience (Geymonat 1954), precursor of modern positivist science (Drake 1978), or maybe an Archimedean (Machamer 1998), who might have used a revised Scholastic method of proof (Wallace 1992)? Or did he have no method and just fly like an eagle in the way that geniuses do (Feyerabend 1975)? Behind each of these claims there was some attempt to place Galileo in an intellectual context that brought out the background to his achievements. Some emphasize his debt to the artisan/engineer practical tradition (Rossi 1962), others his mathematics (Giusti1993, Peterson 2011,, Feldhay 1998, Palmieri 2001, 2003, Renn 2002, Palmerino 2015,), some his mixed (or subalternate) mathematics (Machamer 1978, 1998, Lennox 1986, Wallace 1992), others his debt to atomism (Shea 1972, Redondi 1983), and some his use of Hellenistic and Medieval impetus theory (Duhem 1954, Claggett 1966, Shapere 1974) or the idea that discoveries bring new data into science (Wootton (2015).

Yet most everyone in this tradition seemed to think the three areas—physics, astronomy and methodology—were somewhat distinct and represented different Galilean endeavors. More recent historical research has followed contemporary intellectual fashion and shifted foci bringing new dimensions to our understanding of Galileo by studying his rhetoric (Moss 1993, Feldhay 1998, Spranzi 2004), the power structures of his social milieu (Biagioli 1993, 2006), his personal quest for acknowledgment (Shea and Artigas 2003) and more generally has emphasized the larger social and cultural history, specifically the court and papal culture, in which Galileo functioned (Redondi 1983, Biagioli 1993, 2006, Heilbron 2010).

In an intellectualist recidivist mode, this entry will outline his investigations in physics and astronomy and exhibit, in a new way, how these all cohered in a unified inquiry. In setting this path out I shall show why, at the end of his life, Galileo felt compelled (in some sense of necessity) to write the Discourses Concerning the Two New Sciences , which stands as a true completion of his overall project and is not just a reworking of his earlier research that he reverted to after his trial, when he was blind and under house arrest. Particularly, we shall try to show why both of the two new sciences, especially the first, were so important (a topic not much treated except recently by Biener 2004 and Raphael 2011). In passing, we shall touch on his methodology and his mathematics (and here refer you to some of the recent work by Palmieri 2001, 2003). At the end we shall have some words about Galileo, the Catholic Church and his trial.

The philosophical thread that runs through Galileo’s intellectual life is a strong and increasing desire to find a new conception of what constitutes natural philosophy and how natural philosophy ought to be pursued. Galileo signals this goal clearly when he leaves Padua in 1611 to return to Florence and the court of the Medici and asks for the title Philosopher as well as Mathematician . This was not just a status-affirming request, but also a reflection of his large-scale goal. What Galileo accomplished by the end of his life in 1642 was a reasonably articulated replacement for the traditional set of analytical concepts connected with the Aristotelian tradition of natural philosophy. He offered, in place of the Aristotelian categories, a set of mechanical concepts that were accepted by most everyone who afterwards developed the ‘new sciences’, and which, in some form or another, became the hallmark of the new philosophy. His way of thinking became the way of the scientific revolution (and yes, there was such a ‘revolution’ pace Shapin 1996 and others, cf. selections in Lindberg 1990, Osler 2000.)

Some scholars might wish to describe what Galileo achieved in psychological terms as an introduction of new mental models (Palmieri 2003) or a new model of intelligibility (Machamer 1998, Adams et al . 2017). However phrased, Galileo’s main move was to de-throne the Aristotelian physical categories of the one celestial (the aether or fifth element) and four terrestrial elements (fire, air, water and earth) and their differential directional natures of motion (circular,  and up and down). In their place he left only one element, corporeal matter, and a different way of describing the properties and motions of matter in terms of the mathematics of the equilibria of proportional relations (Palmieri 2001) that were typified by the Archimedian simple machines—the balance, the inclined plane, the lever, and, he includes, the pendulum (Machamer 1998, Machamer and Hepburn 2004, Palmieri 2008). In doing so Galileo changed the acceptable way of talking about matter and its motion, and so ushered in the mechanical tradition that characterizes so much of modern science, even today. But this would take more explaining (Dijksterhuis 1950, Machamer et al. 2000, Gaukroger 2009).

As a main focus underlying Galileo’s accomplishments, it is useful to see him as being interested in finding a unified theory of matter, a mathematical theory of the material stuff that constitutes the whole of the cosmos. Perhaps he didn’t realize that this was his grand goal until the time he actually wrote the Discourses on the Two New Sciences in 1638. Despite working on problems of the nature of matter from 1590 onwards, he could not have written his final work much earlier than 1638, certainly not before The Starry Messenger of 1610, and actually not before the Dialogues on the Two Chief World Systems of 1632. Before 1632, he did not have the theory and evidence he needed to support his claim about unified, singular matter. He had thought deeply about the nature of matter before 1610 and had tried to work out how best to describe matter, but the idea of unified matter theory had to wait on the establishment of principles of matter’s motion on a moving earth. And this he did not do until the Dialogues .

Galileo began his critique of Aristotle in the 1590 manuscript, De Motu . The first part of this manuscript deals with terrestrial matter and argues that Aristotle’s theory has it wrong. For Aristotle, sublunary or terrestrial matter is of four kinds [earth, air, water, and fire] and has two forms, heavy and light, which by nature are different principles of (natural) motion, down and up. Galileo, using an Archimedian model of floating bodies and later the balance, argues that there is only one principle of motion, the heavy ( gravitas ), and that lightness (or levitas ) is to be explained by the heavy bodies moving so as to displace or extrude other bits of matter in such a direction that explains why the other bits rise. So on his view heaviness (or gravity) is the cause of all natural terrestrial motion. But this left him with a problem as to the nature of the heavy, the nature of gravitas ? In De Motu , he argued that the moving arms of a balance could be used as a model for treating all problems of motion. In this model heaviness is the proportionality of weight of one object on one arm of a balance to that of the weight of another body on the other arm of the balance. In the context of floating bodies, weight is the ‘weight’ of one body minus weight of the medium.

Galileo realized quickly these characterizations were insufficient, and so began to explore how heaviness was relative to the different specific gravities of bodies having the same volume. He was trying to figure out what is the concept of heaviness that is characteristic of all matter. What he failed to work out, and this was probably the reason why he never published De Motu , was this positive characterization of heaviness. There seemed to be no way to find standard measures of heaviness that would work across different substances. So at this point he did not have useful replacement categories.

A while later, in his 1600 manuscript, Le Mecaniche (Galileo 1600/1960) he introduces the concept of momento , a quasi force concept that applies to a body at a moment and which is somehow proportional to weight or specific gravity (Galluzzi 1979). Still, he has no good way to measure or compare specific gravities of bodies of different kinds and his notebooks during this early 17 th -century period reflect his trying again and again to find a way to bring all matter under a single proportional measuring scale. He tries to study acceleration along an inclined plane and to find a way to think of what changes acceleration brings. In this regard and during this period he attempts to examine the properties of percussive effect of bodies of different specific gravities, or how they have differential impacts. Yet the details and categories of how to properly treat weight and movement elude him.

One of Galileo’s problems was that the Archimedian simple machines that he was using as his model of intelligibility, especially the balance, are not easily conceived of in a dynamic way (but see Machamer and Woody 1994). Except for the inclined plane, time is not a property of the action of simple machines that one would normally attend to. In discussing a balance, one does not normally think about how fast an arm of the balance descends nor how fast a body on the opposite arm is rising (though Galileo in his Postils to Rocco ca. 1634–45 does; see Palmieri 2005). The converse is also true. It is difficult to model ‘dynamic’ phenomena that deal with the rate of change of different bodies as problems of balance arms moving upwards or downwards because of differential weights. So it was that Galileo’s classic dynamic puzzle about how to describe time and the force of percussion, or the force of body’s impact, would remain unsolved, He could not, throughout his life find systematic relations among specific gravities, height of fall and percussive forces. In the Fifth Day of the Discouses, he presciently explores the concept of the force of percussion . This concept will become, after his death, one of the most fecund ways to think about matter.

In 1603–9, Galileo worked long at doing experiments on inclined planes and most importantly with pendula. The pendulum again exhibited to Galileo that acceleration and, therefore, time is a crucial variable. Moreover, isochrony—equal times for equal lengths of string, despite different weights—goes someway towards showing that time is a possible form for describing the equilibrium (or ratio) that needs to be made explicit in representing motion. It also shows that in at least one case time can displace weight as a crucial variable. Work on the force of percussion and inclined planes also emphasized acceleration and time, and during this time (ca. 1608) he wrote a little treatise on acceleration that remained unpublished.

We see from this period that Galileo’s law of free fall arises out of this struggle to find the proper categories for his new science of matter and motion. Galileo accepts, probably as early as the 1594 draft of Le Mecaniche , that natural motions might be accelerated. But that accelerated motion is properly measured against time is an idea enabled only later, chiefly through his failure to find any satisfactory dependence on place and specific gravity. Galileo must have observed that the speeds of bodies increase as they move downwards and, perhaps, do so naturally, particularly in the cases of the pendulum, the inclined plane, in free fall, and during projectile motion. Also at this time he begins to think about percussive force, the force that a body acquires during its motion that shows upon impact. For many years he thinks that the correct science of these changes should describe how bodies change according to where they are on their paths. Specifically, it seems that height is crucial. Percussive force is directly related to height and the motion of the pendulum seems to involve essentially equilibrium with respect to the height of the bob (and time also, but isochrony did not lead directly to a recognition of time’s importance.)

The law of free fall, expressed as time squared, was discovered by Galileo through the inclined plane experiments (Drake 1999, v. 2), but he attempted to find an explanation of this relation, and the equivalent mean proportional relation, through a velocity-distance relation. His later and correct definition of natural acceleration as dependent on time is an insight gained through recognizing the physical significance of the mean proportional relation (Machamer and Hepburn 2004; for a different analysis of Galileo’s discovery of free fall see Renn et al. 2004.) Yet Galileo would not publish anything making time central to motion until 1638, in Discourses on the Two New Sciences (Galileo 1638/1954.) But let us return to the main matter.

In 1609 Galileo begins his work with the telescope. Many interpreters have taken this to be an interlude irrelevant to his physics. The Starry Messenger , which describes his early telescopic discoveries, was published in 1610. There are many ways to describe Galileo’s findings but for present purposes they are remarkable as his start at dismantling of the celestial/terrestrial distinction (Feyerabend 1975). Perhaps the most unequivocal case of this is when he analogizes the mountains on the moon to mountains in Bohemia. The abandonment of the heaven/earth dichotomy implied that all matter is of the same kind, whether celestial or terrestrial. Further, if there is only one kind of matter there can be only one kind of natural motion, one kind of motion that this matter has by nature. So it has to be that one law of motion will hold for earth, fire and the heavens. This is a far stronger claim than he had made back in 1590. In addition, he described of his discovery of the four moons circling Jupiter, which he called politically the Medicean stars (after the ruling family in Florence, his patrons). In the Copernican system, the earth having a moon revolve around it was unique and so seemingly problematic. Jupiter’s having planets made the earth-moon system non-unique and so again the earth became like the other planets.  Some fascinating background and treatments of this period of Galileo’s life and motivations have recently appeared (Biagoli 2006, Reeves 2008, and the essays in Hessler and De Simone 2013).

In 1611, at the request of Cardinal Robert Bellarmine, the professors at the Collegio Romano confirmed Galileo’s telescopic observations, with a slight dissent from Father Clavius, who felt that the moon’s surface was probably not uneven. Later that year Clavius changed his mind.

A few years later in his Letters on the Sunspots (1612), Galileo enumerated more reasons for the breakdown of the celestial/terrestrial distinction. Basically the ideas here were that the sun has spots ( maculae ) and rotated in circular motion, and, most importantly Venus had phases just like the moon, which was the spatial key to physically locating Venus as being between the Sun and the earth, and as revolving around the Sun. In these letters he claimed that the new telescopic evidence supported the Copernican theory. Certainly the phases of Venus contradicted the Ptolemaic ordering of the planets.

Later in 1623, Galileo argued for a quite mistaken material thesis. In The Assayer , he tried to show that comets were sublunary phenomena and that their properties could be explained by optical refraction. While this work stands as a masterpiece of scientific rhetoric, it is somewhat strange that Galileo should have argued against the super-lunary nature of comets, which the great Danish astronomer Tycho Brahe had demonstrated earlier.

Yet even with all these changes, two things were missing. First, he needed to work out some general principles concerning the nature of motion for this new unified matter. Specifically, given his Copernicanism, he needed to work out, at least qualitatively, a way of thinking about the motions of matter on a moving earth. The change here was not just the shift from a Ptolemaic, Earth-centered planetary system to a Sun-centered Copernican model. For Galileo, this shift was also from a mathematical planetary model to a physically realizable cosmography. It was necessary for him to describe the planets and the earth as real material bodies. In this respect Galileo differed dramatically from Ptolemy, Copernicus, or even Tycho Brahe, who had demolished the crystalline spheres by his comets-as-celestial argument and flirted with physical models (Westman 1976). So on the new Galilean scheme there is only one kind of matter, and it may have only one kind of motion natural to it. Therefore, he had to devise (or shall we say, discover) principles of local motion that will fit a central sun, planets moving around that sun, and a daily whirling earth.

This he did by introducing two new principles. In Day One of his Dialogues on the Two Chief World Systems (1632), Galileo argued that all natural motion is circular. Then, in Day Two, he introduced his version of the famous principle of the relativity of observed motion. This latter held that motions in common among bodies could not be observed. Only those motions differing from a shared common motion could be seen as moving. The joint effect of these two principles was to say that all matter shares a common motion, circular, and so only motions different from the common, say up and down motion, could be directly observed. Of course, neither of the principles originated with Galileo. They had predecessors. But no one needed them for the reasons that he did, namely that they were necessitated by a unified cosmological matter.

In Day Three, Galileo dramatically argues for the Copernican system. Salviati, the persona of Galileo, has Simplicio, the ever astounded Aristotelian, make use of astronomical observations, especially the facts that Venus has phases and that Venus and Mercury are never far from the Sun, to construct a diagram of the planetary positions. The resulting diagram neatly corresponds to the Copernican model. Earlier in Day One, he had repeated his claims from The Starry Messenger , noting that the earth must be like the moon in being spherical, dense and solid, and having rugged mountains. Clearly the moon could not be a crystalline sphere as held by some Aristotelians.

In the Dialogues , things are more complicated than we have just sketched. Galileo, as noted, argues for a circular natural motion, so that all things on the earth and in the atmosphere revolve in a common motion with the earth so that the principle of the relativity of observed motion will apply to phenomena such as balls dropped from the masts of moving ships. Yet he also introduces at places a straight-line natural motion. For example, in Day Three, he gives a quasi account for a Coriolis-type effect for the winds circulating about the earth by means of this straight-line motion (Hooper 1998). Further, in Day Four, when he is giving his proof of the Copernican theory by sketching out how the three-way moving earth mechanically moves the tides, he nuances his matter theory by attributing to the element water the power of retaining an impetus for motion such that it can provide a reciprocal movement once it is sloshed against a side of a basin. This was not Galileo’s first dealing with water. We saw it in De Motu in 1590, with submerged bodies, but more importantly he learned much more while working through his dispute over floating bodies ( Discourse on Floating Bodies , 1612). In fact a large part of this debate turned on the exact nature of water as matter, and what kind of mathematical proportionality could be used to correctly describe it and bodies moving in it (cf. Palmieri, 1998, 2004a).

The final chapter of Galileo’s scientific story comes in 1638 with the publication of Discourses of the Two New Sciences . The second science, discussed (so to speak) in the last two days, dealt with the principles of local motion. These have been much commented upon in the Galilean literature. Here is where he enunciates the law of free fall, the parabolic path for projectiles and his physical “discoveries” (Drake 1999, v. 2). But the first two days, the first science, has been much misunderstood and little discussed. This first science, misleadingly, has been called the science of the strength of materials, and so seems to have found a place in history of engineering, since such a course is still taught today. However, this first science is not about the strength of materials per se . It is Galileo’s attempt to provide a mathematical science of his unified matter. (See Machamer 1998, Machamer and Hepburn 2004, and the detailed work spelling this out by Biener 2004.) Galileo realizes that before he can work out a science of the motion of matter, he must have some way of showing that the nature of matter may be mathematically characterized. Both the mathematical nature of matter and the mathematical principles of motion he believes belong to the science of mechanics, which is the name he gives for this new way of philosophizing. Remember that specific gravities did not work.

So it is in Day One that he begins to discuss how to describe, mathematically (or geometrically), the causes of how beams break. He is searching for the mathematical description of the essential nature of matter. He rules out certain questions that might use infinite atoms as basis for this discussion, and continues on giving reasons for various properties that matter has. Among these are questions of the constitution of matter, properties of matter due to its heaviness, the properties of the media within which bodies move and what is the cause of a body’s coherence as a single material body. The most famous of these discussions is his account of acceleration of falling bodies, that whatever their weight would fall equally fast in a vacuum. The Second Day lays out the mathematical principles concerning how bodies break. He does this all by reducing the problems of matter to problems of how a lever and a balance function. Something he had begun back in 1590, though this time he believes he is getting it right, showing mathematically how bits of matter solidify and stick together, and do so by showing how they break into bits. The ultimate explanation of the “sticking” eluded him since he felt he would have to deal with infinitesimals to really solve this problem.

The second science, Days Three and Four of Discorsi , dealt with proper principles of local motion, but this was now motion for all matter (not just sublunary stuff) and it took the categories of time and acceleration as basic. Interestingly Galileo, here again, revisited or felt the need to include some anti-Aristotelian points about motion as he had done back in 1590. The most famous example of his doing this, is his “beautiful thought experiment”, whereby he compares two bodies of the same material of different sizes and points out that according to Aristotle they fall at different speeds, the heavier one faster. Then, he says, join the bodies together. In this case the lightness of the small one ought to slow down the faster larger one, and so they together fall as a speed less than the heavy fell in the first instance. Then his punch line: but one might also conceive of the two bodies joined as being one larger body, in which case it would fall even more quickly. So there is a contradiction in the Aristotelian position (Palmieri 2005). His projected Fifth Day would have treated the grand principle of the power of matter in motion due to impact. He calls it the force of percussion, which deals with two bodies interacting. This problem he does not solve, and it won’t be solved until René Descartes, probably following Isaac Beeckman, turns the problem into finding the equilibrium points for colliding bodies.

The sketch above provides the basis for understanding Galileo’s changes. He has a new science of matter, a new physical cosmography, and a new science of local motion. In all these he is using a mathematical mode of description based upon, though somewhat changed from, the proportional geometry of Euclid, Book VI and Archimedes (for details on the change see Palmieri 2002).

It is in this way that Galileo developed the new categories of the mechanical new science, the science of matter and motion. His new categories utilized some of the basic principles of traditional mechanics, to which he added the category of time and so emphasized acceleration. But throughout, he was working out the details about the nature of matter so that it could be understood as uniform and treated in a way that allowed for coherent discussion of the principles of motion. That a unified matter became accepted and its nature became one of the problems for the ‘new science’ that followed was due to Galileo. Thereafter, matter really mattered.

No account of Galileo’s importance to philosophy can be complete if it does not discuss Galileo’s condemnation and the Galileo affair (Finocchiaro 1989). The end of the episode is simply stated. In late 1632, after publishing Dialogues on the Two Chief World Systems , Galileo was ordered to go to Rome to be examined by the Holy Office of the Inquisition. In January 1633, a very ill Galileo made an arduous journey to Rome. Finally, in April 1633 Galileo was called before the Holy Office. This was tantamount to a charge of heresy, and he was urged to repent (Shea and Artigas, 183f). Specifically, he had been charged with teaching and defending the Copernican doctrine that holds that the Sun is at the center of the universe and that the earth moves. This doctrine had been deemed heretical in 1616, and Copernicus’ book had been placed on the Index of Prohibited Books, pending correction.

Galileo was called four times for a hearing; the last was on June 21, 1633. The next day, 22 June, Galileo was taken to the church of Santa Maria sopra Minerva, and ordered to kneel while his sentence was read. It was declared that he was “vehemently suspect of heresy”. Galileo was made to recite and sign a formal abjuration:

I have been judged vehemently suspect of heresy, that is, of having held and believed that the sun in the centre of the universe and immoveable, and that the earth is not at the center of same, and that it does move. Wishing however, to remove from the minds of your Eminences and all faithful Christians this vehement suspicion reasonably conceived against me, I abjure with a sincere heart and unfeigned faith, I curse and detest the said errors and heresies, and generally all and every error, heresy, and sect contrary to the Holy Catholic Church. (Quoted in Shea and Artigas 194)

Galileo was not imprisoned but had his sentence commuted to house arrest. In December 1633 he was allowed to retire to his villa in Arcetri, outside of Florence. During this time he finished his last book, Discourses on the Two New Sciences , which was published in 1638, in Holland, by Louis Elzivier. The book does not mention Copernicanism at all, and Galileo professed amazement at how it could have been published. He died on January 8, 1642.

There has been much controversy over the events leading up to Galileo’s trial, and it seems that each year we learn more about what actually happened. There is also controversy over the legitimacy of the charges against Galileo, both in terms of their content and judicial procedure. The summary judgment about this latter point is that the Church most probably acted within its authority and on ‘good’ grounds given the condemnation of Copernicus, and, as we shall see, the fact that Galileo had been warned by Cardinal Bellarmine earlier in 1616 not to defend or teach Copernicanism. There were also a number of political factors given the Counter Reformation, the 30 Years War (Miller 2008), and the problems with the papacy of Urban VIII that served as further impetus to Galileo’s condemnation (McMullin, ed. 2005). It has even been argued (Redondi 1983) that the charge of Copernicanism was a compromise plea bargain to avoid the truly heretical charge of atomism. Though this latter hypothesis has not found many willing supporters.

Legitimacy of the content, that is, of the condemnation of Copernicus, is much more problematic. Galileo had addressed this problem in 1615, when he wrote his Letter to Castelli (which was transformed into the Letter to the Grand Duchess Christina ). In this letter he had argued that, of course, the Bible was an inspired text, yet two truths could not contradict one another. So in cases where it was known that science had achieved a true result, the Bible ought to be interpreted in such a way that makes it compatible with this truth. The Bible, he argued, was an historical document written for common people at an historical time, and it had to be written in language that would make sense to them and lead them towards the true religion.

Much philosophical controversy, before and after Galileo’s time, revolves around this doctrine of the two truths and their seeming incompatibility. Which of course, leads us right to such questions as: “What is truth?” and “How is truth known or shown?”

Cardinal Bellarmine was willing to countenance scientific truth if it could be proven or demonstrated (McMullin 1998). But Bellarmine held that the planetary theories of Ptolemy and Copernicus (and presumably Tycho Brahe) were only hypotheses and due to their mathematical, purely calculatory character were not susceptible to physical proof. This is a sort of instrumentalist, anti-realist position (Duhem 1985, Machamer 1976). There are any number of ways to argue for some sort of instrumentalism. Duhem (1985) himself argued that science is not metaphysics, and so only deals with useful conjectures that enable us to systematize the phenomena. Subtler versions, without an Aquinian metaphysical bias, of this position have been argued subsequently and more fully by van Fraassen (1996) and others. Less sweepingly, it could reasonably be argued that both Ptolemy and Copernicus’ theories were primarily mathematical, and that what Galileo was defending was not Copernicus’ theory per se, but a physical realization of it. In fact, it might be better to say the Copernican theory that Galileo was constructing was a physical realization of parts of Copernicus’ theory, which, by the way, dispensed with all the mathematical trappings (eccentrics, epicycles, Tusi couples and the like). Galileo would be led to such a view by his concern with matter theory. Of course, put this way we are faced with the question of what constitutes identity conditions for a theory, or being the same theory. There is clearly a way in which Galileo’s Copernicus is not Copernicus and most certainly not Kepler.

The other aspect of all this which has been hotly debated is: what constitutes proof or demonstration of a scientific claim? In 1616, the same year that Copernicus’ book was placed on the Index of Prohibited Books, Galileo was called before Cardinal Robert Bellarmine, head of the Holy Office of the Inquisition and warned not to defend or teach Copernicanism. During this year Galileo also completed a manuscript, On the Ebb and Flow of the Tides . The argument of this manuscript will turn up 17 years later as day Four of Galileo’s Dialogues concerning the Two Chief World Systems . This argument, about the tides, Galileo believed provided proof of the truth of the Copernican theory. But insofar as it possibly does, it provides an argument for the physical plausibility of Galileo’s Copernican theory. Let’s look more closely at his argument.

Galileo argues that the motion of the earth (diurnal and axial) is the only conceivable (or maybe plausible) physical cause for the reciprocal regular motion of the tides. He restricts the possible class of causes to mechanical motions, and so rules out Kepler’s attribution of the moon as a cause. How could the moon without any connection to the seas cause the tides to ebb and flow? Such an explanation would be the invocation of magic or occult powers. So the motion of the earth causes the waters in the basins of the seas to slosh back and forth, and since the earth’s diurnal and axial rotation is regular, so are the periods of the tides; the backward movement is due to the residual impetus built up in the water during its slosh. Differences in tidal flows are due to the differences in the physical conformations of the basins in which they flow (for background and more detail, see Palmieri 1998).

Albeit mistaken, Galileo’s commitment to mechanically intelligible causation makes this is a plausible argument. One can see why Galileo thinks he has some sort of proof for the motion of the earth, and therefore for Copernicanism. Yet one can also see why Bellarmine and the instrumentalists would not be impressed. First, they do not accept Galileo’s restriction of possible causes to mechanically intelligible causes. Second, the tidal argument does not directly deal with the annual motion of the earth about the sun. And third, the argument does not touch anything about the central position of the sun or about the periods of the planets as calculated by Copernicus. So at its best, Galileo’s argument is an inference to the best partial explanation of one point in Copernicus’ theory. Yet when this argument is added to the earlier telescopic observations that show the improbabilities of the older celestial picture, to the fact that Venus has phases like the moon and so must revolve around the sun, to the principle of the relativity of perceived motion which neutralizes the physical motion arguments against a moving earth, it was enough for Galileo to believe that he had the necessary proof to convince the Copernican doubters. Unfortunately, it was not until after Galileo’s death and the acceptance of a unified material cosmology, utilizing the presuppositions about matter and motion that were published in the Discourses on the Two New Sciences, that people were ready for such proofs. But this could occur only after Galileo had changed the acceptable parameters for gaining knowledge and theorizing about the world. 

To read many of the documents of Galileo’s trial see Finocchiaro 1989, and Mayer 2012. To understand the long, tortuous, and fascinating aftermath of the Galileo affair see Finocchiaro 2005, and for John Paul II’s attempt see George Coyne’s article in McMullin 2005.

Primary Sources: Galileo’s Works

The main body of Galileo’s work is collected in Le Opere di Galileo Galilei , Edizione Nazionale, 20 vols., edited by Antonio Favaro, Florence: Barbera, 1890-1909; reprinted 1929-1939 and 1964–1966.

• 1590, On Motion , translated I.E. Drabkin, Madison: University of Wisconsin Press, 1960.
• 1600, On Mechanics , S. Drake (trans.), Madison: University of Wisconsin Press, 1960.
• 1610, The Starry Messenger , A. van Helden (ed.), Chicago: University of Chicago Press, 1989.
• 1613, Letters on the Sunspots , selections in S. Drake, (ed.), The Discoveries and Opinions of Galileo , New York: Anchor, 1957.
• 1623, Il Saggiatore , The Assayer , translated by Stillman Drake, in The Controversy of the Comets of 1618 , Philadelphia: The University of Pennsylvania Press 1960.
• 1632, Dialogue Concerning the Two Chief World Systems , S. Drake (trans.), Berkeley: University of California Press, 1967.
• 1638, Dialogues Concerning Two New Sciences , H. Crew and A. de Salvio (trans.), Dover Publications, Inc., New York, 1954, 1974. A better translation is: Galilei, Galileo. [ Discourses on the ] Two New Sciences , S. Drake (trans.), Madison: University of Wisconsin Press, 1974; 2nd edition, 1989 & 2000 Toronto: Wall and Emerson.

Secondary Sources

• Adams, Marcus P., Zvi Biener, Uljana Feest, and Jacqueline A. Sullivan (eds.), 2017, Eppur si Muove: Doing History and Philosophy of Science with Peter Machamer , Dordrecht: Springer.
• Bedini, Silvio A., 1991, The Pulse of Time: Galileo Galilei, the Determination of Longitude, and the Pendulum Clock , Florence: Olschki.
• –––, 1967, Galileo and the Measure of Time , Florence: Olschki.
• Biagioli, Mario, 1993, Galileo Courtier , Chicago: University of Chicago Press.
• –––, 1990, “Galileo’s System of Patronage,” History of Science , 28: 1–61.
• –––, 2006, Galileo’s Instruments of Credit :Tekescopes, Images, Secrecy , Chicago: University of Chicago Press.
• Biener, Zvi, 2004, “Galileo’s First New Science: the Science of Matter,” Perspectives on Science , 12(3): 262–287.
• Carugo, Adriano and Crombie, A. C., 1983, “The Jesuits and Galileo’s Ideas of Science and Nature,” Annali dell’Istituto e Museo di Storia della Scienza di Firenze , 8(2): 3–68.
• Claggett, Marshall, 1966, The Science of Mechanics in the Middle Ages , Madison: University of Wisconsin Press.
• Crombie, A. C., 1975, “Sources of Galileo’s Early Natural Philosophy,” in Reason, Experiment, and Mysticism in the Scientific Revolution , Edited by Maria Luisa Righini Bonelli and William R. Shea, pp. 157–175. New York: Science History Publications.
• Dijksterhuis, E.J., 1961 [1950], The Mechanization of the World Picture , translated by C Dikshoorn, Oxford: Oxford University Press.
• Drake, Stillman, 1957, Discoveries and Opinions of Galileo , Garden City, NY: Doubleday.
• –––, 1978, Galileo at Work: His Scientific Biography , Chicago: University of Chicago Press.
• –––, 1999, Essays on Galileo and the history and philosophy of science , N.M. Swerdlow and T.H. Levere, eds., 3 volumes, Toronto: University of Toronto Press.
• Duhem, Pierre, 1954, Le Systeme du monde , 6 volumes, Paris: Hermann.
• –––, 1985, To Save the Phenomena: An Essay on the Idea of Physical Theory from Plato to Galileo , translated Roger Ariew, Chicago: University of Chicago Press.
• Feldhay, Rivka, 1995, Galileo and the Church: Political Inquisition or Critical Dialogue , New York, NY: Cambridge University Press.
• –––, 1998, “The use and abuse of mathematical entities: Galileo and the Jesuits revisited,” in Machamer 1998.
• Feyerabend, Paul, 1975, Against Method , London: Verso, and New York: Humanities Press.
• Finocchiaro, Maurice A., 2005, Retrying Galileo, 1633–1992 , Berkeley: University of California Press
• –––, 1989, The Galileo Affair , Berkeley and Los Angeles: University of California Press,
• –––, 1980, Galileo and the Art of Reasoning , Dordrecht: Reidel.
• Galluzzi, Paolo, 1979, Momento: Studi Galileiani , Rome: Ateno e Bizzarri.
• Gaukroger, Stephen, 2009, The Emergence of a Scientific Culture: Science and the Shaping of Modernity 1210–1685 , Oxford: Oxford University Press.
• Geymonat, Ludovico, 1954, Galileo: A Biography and Inquiry into his Philosophy of Science , translated S. Drake, New York: McGraw Hill.
• Giusti, Enrico, 1993, Euclides Reformatus. La Teoria delle Proporzioni nella Scuola Galileiana , Torino: Bottati-Boringhieri.
• Heilbron, J.L., 2010, Galileo , Oxford: Oxford University Press.
• Hessler, John W. and Daniel De Simone (eds.), 2013, Galileo Galilei, The Starry Messenger, From Doubt to Astonishment, with the symposium proceedings Library of Congress, Levenger Press
• Hooper, Wallace, 1998, “Inertial problems in Galileo’s preinertial framework,” in Machamer 1998.
• Koyré, Alexander, 1939, Etudes Galileennes , Paris Hermann; translated John Mepham, Galileo Studies , Atlantic Highlands, N.J.: Humanities Press, 1978
• Lennox, James G., 1986, “Aristotle, Galileo and the ‘Mixed Sciences’ in William Wallace, ed. Reinterpreting Galileo , Washington, D.C.: The Catholic University of America Press.
• Lindberg, David C. and Robert S. Westman (eds.), 1990, Reappraisals of the Scientific Revolution , Cambridge: Cambridge University Press.
• Machamer, Peter, 1976, “Fictionalism and Realism in 16th Century Astronomy,” in R.S. Westman (ed.), The Copernican Achievement , Berkeley: University of California Press, 346–353.
• –––, 1978, “Galileo and the Causes,” in Robert Butts and Joseph Pitt (eds.), New Perspectives on Galileo , Dordrecht: Kleuwer.
• –––, 1991, “The Person Centered Rhetoric of the 17th Century,” in M. Pera and W. Shea (eds.), Persuading Science: The Art of Scientific Rhetoric , Canton, MA: Science History Publications.
• –––, and Andrea Woody, 1994, “A Model of intelligibility in Science: Using Galileo’s Balance as a Model for Understanding the Motion of Bodies,” Science and Education , 3: 215–244.
• ––– (ed.), 1998, “Introduction,” and “Galileo, Mathematics and Mechanism,” Cambridge Companion to Galileo , Cambridge: Cambridge University Press.
• –––, 1999, “Galileo’s Rhetoric of Relativity,” Science and Education , 8(2): 111–120; reprinted in Enrico Gianetto, Fabio Bevilacqua and Michael Matthews, eds. Science Education and Culture: The Role of History and Philosophy of Science , Dordrecht: Kluwer, 2001.
• Machamer, P., Lindley Darden, and Carl Craver, 2000, “Thinking about Mechanisms,” Philosophy of Science , 67: 1–25.
• Machamer, P., and Brian Hepburn, 2004, “Galileo and the Pendulum; Latching on to Time,” Science and Education , 13: 333–347; also in Michael R. Matthews (ed.), Proceedings of the International Pendulum Project (Volume 2), Sydney, Australia: The University of South Wales, 2002, 75–83.
• McMullin, Ernan (ed.), 1964, Galileo Man of Science , New York: Basic Books.
• –––, 1998, “Galileo on Science and Scripture,” in Machamer 1998.
• ––– (ed.), 2005, The Church and Galileo: Religion and Science , Notre Dame: University of Notre Dame Press.
• Mayer, Thomas F. (ed.), 2012, The Trial of Galileo 1612-1633 , North York, Ontario: The University of Toronto Press.
• Miller, David Marshall, 2008, “The Thirty Years War and the Galileo Affair,” History of Science , 46: 49-74.
• Moss, Jean Dietz, 1993, Novelties in the Heavens , Chicago, University of Chicago Press.
• Osler, Margaret, ed., 2000, Rethinking the Scientific Revolution , Cambridge: Cambridge University Press
• Palmerino, Carla Rita, 2016, “Reading the Book of Nature: The Ontological and Epistemological Underpinnings of Galileo’s Mathematical Realism,” in G. Gorham, B. Hill, E. Slowik and K. Watters (eds.), The Language of Nature: Reassessing the Mathematization of Natural Philosophy the Seventeenth Century , Minneapolis: University of Minnesota Press, pp. 29-50.
• Palmerino, Carla Rita and J.M.M.H. Thijssen, 2004, The Reception of the Galilean Science of Motion in Seventeenth-Century Europe , Dordrecht: Kluwer.
• Palmieri, Paolo, 2008, Reenacting Galileo’s Experiments: Rediscovering the Techniques of Seventeenth-Century Science , Lewiston, NY: Edwin Mellen Press
• –––, 1998, “Re-examining Galileo’s Theory of Tides,” Archive for History of Exact Sciences , 53: 223–375.
• –––, 2001, “The Obscurity of the Equimultiples: Clavius’ and Galileo’s Foundational Studies of Euclid’s Theory of Proportions,” Archive for the History of the Exact Sciences , 55(6): 555–597.
• –––, 2003, “Mental Models in Galileo’s Early Mathematization of Nature,” Studies in History and Philosophy of Science , 34: 229–264.
• –––, 2004a, “The Cognitive Development of Galileo’s Theory of Buoyancy,” Archive for the History of the Exact Sciences , 59: 189–222.
• –––, 2005, “‘Spuntar lo scoglio piu duro’: did Galileo ever think the most beautiful thought experiment in the history of science?” Studies in History and Philosophy of Science , 36(2): 223–240.
• Peterson Mark A., 2011, Galileo’s Muse: Renaissance Mathematics and the Arts , Cambridge, MA: Harvard University Press.
• Redondi, Pietro, 1983, Galileo eretico , Torino: Einaudi; translated by Raymond Rosenthal, Galileo Heretic , Princeton: Princeton University Press, 1987.
• Raphael, Renee Jennifer, 2011, “Making sense of Day 1 of the Two New Sciences: Galileo’s Aristotelian-inspired agenda and his Jesuit readers,” Studies in History and Philosophy of Science , 42: 479-491.
• Renn, J. & Damerow, P. & Rieger, S., 2002, ‘Hunting the White Elephant: When and How did Galileo Discover the Law of Fall?’, in J. Renn (ed.), Galileo in Context , Cambridge University Press, Cambridge, 29–149.
• Reeves, Eileen, 2008, Galileo’s Glass Works: The telescope and the mirror , Cambridge, MA: Harvard University Press.
• Rossi, Paolo, 1962, I Filosofi e le Macchine , Milan: Feltrinelli; 1970, translated by S. Attanasio, Philosophy, Technology and the Arts in the Early Modern Era , New York: Harper.
• Segré, Michael, 1998, “The Neverending Galileo Story” in Machamer 1998.
• –––, 1991, In the Wake of Galileo , New Brunswick: Rutgers University Press.
• Settle, Thomas B., 1967, “Galileo’s Use of Experiment as a Tool of Investigation,” in McMullin 1967.
• –––, 1983, “Galileo and Early Experimentation,” in Springs of Scientific Creativity: Essays on Founders of Modern Science , Rutherford Aris, H. Ted Davis, and Roger H. Stuewer (eds.), Minneapolis: University of Minnesota Press, pp. 3–20.
• –––, 1992, “Experimental Research and Galilean Mechanics,” in Galileo Scientist: His Years at Padua and Venice , Milla Baldo Ceolin (ed.), Padua: Istituto Nazionale di Fisica Nucleare; Venice: Istituto Venet o di Scienze, Lettere ed Arti; Padua: Dipartimento di Fisica, pp. 39–57.
• Shapere, Dudley, 1974, Galileo: A Philosophical Study , Chicago: University of Chicago Press.
• Shapin, Steve, 1996, The Scientific Revolution , Chicago: University of Chicago Press.
• Shea, William, 1972, Galileo’s Intellectual Revolution: Middle Period (1610–1632) , New York: Science History Publications.
• Shea, William & Marinao Artigas, 2003, Galileo in Rome: The Rise and fall of a Troublesome Genius , Oxford: Oxford University Press.
• Sobel, Dava, 1999, Galileo’s Daughter , New York: Walker and company
• Spranzi, Marta, 2004, Galilee: “Le Dialogues sur les deux grands systemes du monde”: rhetorique, dialectique et demenstration , Paris: PUF.
• Van Fraassen, Bas C., 1996, The Scientific Image , Oxford: Oxford University Press.
• Wallace, William A., 1984, Galileo and his Sources: The Heritage of the Collegio Romano in Galileo’s Science , Princeton: Princeton University Press.
• –––, 1992, Galileo’s Logic of Discovery and Proof: The Background, Content and Use of His Appropriated Treatises on Aristotle’s Posterior Analytics , Dordrecht; Boston: Kluwer Academic.
• Westman, Robert (ed.), 1976, The Copernican Achievement , University of California Press.
• Wisan, W. L., 1974, “The New Science of Motion: A Study of Galileo’s De motu locali,” Archive for History of Exact Sciences , 13(2/3): 103–306.
• Woottron, David, 2015, The Invention of Science , New York: Harper.

How to cite this entry . Preview the PDF version of this entry at the Friends of the SEP Society . Look up this entry topic at the Internet Philosophy Ontology Project (InPhO). Enhanced bibliography for this entry at PhilPapers , with links to its database.

• Galileo Galilei’s Notes on Motion , Joint Project of Biblioteca Nazionale Centrale, Florence Istituto e Museo di Storia della Scienza, Florence Max Planck Institute for the History of Science, Berlin.
• The Galileo Project , contains Dava Sobel’s translations of all 124 letters from Suor Maria Celeste to Galileo in the sequence in which they were written, maintained by Albert Van Helden.
• Galileo Galilei , The Institute and Museum of the History of Science of Florence, Italy.

Copernicus, Nicolaus | -->matter --> | natural philosophy: in the Renaissance | religion: and science

Acknowledgments

Thanks to Zvi Biener and Paolo Palmieri for commenting on earlier drafts of this entry.

Copyright © 2017 by Peter Machamer < machamerpeter @ gmail . com >

Support SEP

Mirror sites.

View this site from another server:

• Info about mirror sites

The Stanford Encyclopedia of Philosophy is copyright © 2016 by The Metaphysics Research Lab , Center for the Study of Language and Information (CSLI), Stanford University

Library of Congress Catalog Data: ISSN 1095-5054

 MacTutor

Galileo galilei.

About ten months ago a report reached my ears that a certain Fleming had constructed a spyglass by means of which visible objects, though very distant from the eye of the observer, were distinctly seen as if nearby. Of this truly remarkable effect several experiences were related, to which some persons believed while other denied them. A few days later the report was confirmed by a letter I received from a Frenchman in Paris, Jacques Badovere, which caused me to apply myself wholeheartedly to investigate means by which I might arrive at the invention of a similar instrument. This I did soon afterwards, my basis being the doctrine of refraction.

In about two months, December and January, he made more discoveries that changed the world than anyone has ever made before or since.

I hold that the Sun is located at the centre of the revolutions of the heavenly orbs and does not change place, and that the Earth rotates on itself and moves around it. Moreover ... I confirm this view not only by refuting Ptolemy 's and Aristotle 's arguments, but also by producing many for the other side, especially some pertaining to physical effects whose causes perhaps cannot be determined in any other way, and other astronomical discoveries; these discoveries clearly confute the Ptolemaic system, and they agree admirably with this other position and confirm it.

Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these one is wandering in a dark labyrinth.

I assume that the speed acquired by the same movable object over different inclinations of the plane are equal whenever the heights of those planes are equal.

The time in which a certain distance is traversed by an object moving under uniform acceleration from rest is equal to the time in which the same distance would be traversed by the same movable object moving at a uniform speed of one half the maximum and final speed of the previous uniformly accelerated motion.

References ( show )

• S Drake, Biography in Dictionary of Scientific Biography ( New York 1970 - 1990) . See THIS LINK .
• S Drake, Galileo at Work: His Scientific Biography ( Chicago, Ill.-London, 1981) .
• Biography in Encyclopaedia Britannica. http://www.britannica.com/biography/Galileo-Galilei
• W Brandmüller and E J Greipl, Copernico, Galilei e la Chiesa : Fine della controversia (1820) : gli atti del Sant'Uffizio ( Florence, 1992) .
• M Bucciantini, Contro Galileo : Alle origini dell'affare ( Florence, 1995) .
• T Campanella, A defense of Galileo, the mathematician from Florence ( Notre Dame, IN, 1994) .
• S Drake, Galileo Studies: Personality, Tradition, and Revolution (1970) .
• S Drake, Galileo ( Oxford, 1980) .
• S Drake, Galileo : pioneer scientist ( Toronto, ON, 1990) .
• S Drake, Galileo : Past Masters ( New York, 1980) .
• A Fantoli, Galileo: For Copernicanism and for the Church ( Vatican, 1994) .
• A Fantoli, Galileo : For Copernicanism and for the Church ( Vatican City, 1994) .
• M A Finocchiaro, Galileo and the art of reasoning : Rhetorical foundations of logic and scientific method ( Dordrecht-Boston, Mass., 1980) .
• L Geymonat, Galileo Galilei ( New York, 1965) .
• A Koyré, Galileo studies ( Atlantic Highlands, N.J., 1978) .
• P Machamer ( ed. ) , The Cambridge companion to Galileo ( Cambridge, 1998) .
• P Redondi, Galileo : heretic ( Princeton, NJ, 1987) .
• C A Ronan, Galileo (1974) .
• E Schmutzer and W Schütz, Galileo Galilei ( German ) ( Thun, 1989) .
• M Sharratt, Galileo : Decisive Innovator ( Cambridge, 1994) .
• W R Shea, Galileo's intellectual revolution. Middle period, 1610 - 1632 ( New York, 1977) .
• R S Westfall, Essays on the trial of Galileo ( Vatican, 1989) .
• E Agazzi, Was Galileo a realist?, Physis Riv. Internaz. Storia Sci. ( N.S. ) 31 (1) (1994) , 273 - 296 .
• A V Akhutin, Galileo's experiment, Scientia ( Milano ) 117 (5 - 8) (1982) , 287 - 311 .
• G Aquilecchia, Galileo's 'Chief systems' and Bruno's 'Supper' ( toward a thematical-structural comparison ) ( Italian ) , Nuncius Ann. Storia Sci. 10 (2) (1995) , 485 - 496 .
• U Baldini, Additamenta Galilaeana. II, Galileo in letters of the Elector of Cologne and of Ricardo de Burgo to Christopher Grienberger ( Italian ) , Nuncius Ann. Storia Sci. 2 (1) (1987) , 3 - 36 .
• U Barcaro, Galileo and the biological world ( Italian ) , Physis - Riv. Internaz. Storia Sci. 24 (3) (1982) , 357 - 379 .
• U Barcaro, The properties of circular motion in Galileo's 'Discourses' ( Italian ) , Physis - Riv. Internaz. Storia Sci. 24 (1) (1982) , 5 - 16 .
• U Barcaro, The concept of inertia in the 'Discourses' of Galileo ( Italian ) , Physis - Riv. Internaz. Storia Sci. 22 (3 - 4) (1980) , 325 - 342 .
• F J Baumgartner, Galileo's French correspondents, Ann. of Sci. 45 (2) (1988) , 169 - 182 .
• D A Bayuk, The controversy between Vincenzo Galilei and Gioseffo Zarlino and its influence on the theoretical thought of Galileo Galilei ( Russian ) , Voprosy Istor. Estestvoznan. i Tekhn. (1) (1993) , 46 - 56 .
• M Biagioli, New documents on Galileo, Nuncius Ann. Storia Sci. 6 (2) (1991) , 157 - 169 .
• M Biagioli, Galileo the emblem maker, Isis 81 (307) (1990) , 230 - 258 .
• M Biagioli, Galileo's system of patronage, Hist. of Sci. 28 (79 , 1) (1990) , 1 - 62 .
• T Bolelli, Lingua e stile di Galileo, Nuovo Cimento (10) 2 (1955) , 1173 - 1192 .
• P G Bordoni, Galileo instauratore della meccanica, Ricerca Sci. 26 (1956) , 1378 - 1391 .
• H I Brown, Galileo, the elements, and the tides, Studies in Hist. and Philos. Sci. 7 (4) (1976) , 337 - 351 .
• V Cappelletti, Galileo's trial ( Italian ) , Arch. Internat. Hist. Sci. 33 (110) (1983) , 30 - 35 .
• M De Caro, Galileo's mathematical Platonism, in Philosophy of mathematics ( Vienna, 1993) , 13 - 22 .
• E Carruccio, Galileo precursore della teoria degli insiemi ( Italian ) , Boll. Un. Mat. Ital. (2) 4 (1942) , 175 - 187 .
• A Chalmers and R Nicholas, Galileo on the dissipative effect of a rotating earth, Stud. Hist. Philos. Sci. 14 (4) (1983) , 315 - 340 .
• M Clavelin, Galilée et la mécanisation du système du monde, in Proceedings of the 1978 Pisa Conference on the History and Philosophy of Science I ( Dordrecht- Boston, Mass., 1981) , 229 - 251 .
• J A Coffa, Galileo's concept of inertia, Physis - Riv. Internaz. Storia Sci. 10 (1968) , 261 - 281 .
• A Coppola and A Drago, Did Galileo invent the principle of inertia? Proposal for a new interpretation of his works ( Italian ) , Rend. Accad. Naz. Sci. XL Mem. Sci. Fis. Natur. (5) 9 (1985) , 319 - 327 .
• P Costabel, L'atomisme, face cachée de la condamnation de Galilée?, C. R. Acad. Sci. Sér. Gén. Vie Sci. 4 (4) (1987) , 349 - 365 .
• A C Crombie, Philosophical presuppositions and shifting interpretations of Galileo, in Proceedings of the 1978 Pisa Conference on the History and Philosophy of Science I ( Dordrecht- Boston, Mass., 1981) , 271 - 286 .
• R Devadason, The life history and contributions of a mathematician whom I admire : Galileo Galilei, Menemui Mat. 5 (1) (1983) , 16 - 24 .
• S Drake, Galileo's first telescopic observations, Journal for the history of astronomy 7 (1976) , 153 - 168 .
• S Drake, Galileo's gleanings VI : Galileo's first telescope at Padua and Venive, Isis 50 (1959) , 245 - 254 .
• S Drake, Galileo, Kepler, and the phases of Venus, Journal for the history of astronomy 15 (1984) , 198 - 208 .
• S Drake, Galileo and satellite prediction, Journal for the history of astronomy 10 (1979) , 75 - 95 .
• S Drake, Hipparchus- Geminus- Galileo, Stud. Hist. Philos. Sci. 20 (1) (1989) , 47 - 56 .
• S Drake, Galileo's constant, Nuncius Ann. Storia Sci. 2 (2) (1987) , 41 - 54 .
• S Drake, Galileo and mathematical physics, in Science and philosophy ( Milan, 1985) , 627 - 642 .
• S Drake, Galileo's steps to full Copernicanism, and back, Stud. Hist. Philos. Sci. 18 (1) (1987) , 93 - 105 .
• S Drake, Galileo's pre-Paduan writings : years, sources, motivations, Stud. Hist. Philos. Sci. 17 (4) (1986) , 429 - 448 .
• S Drake, Galileo's physical measurements, Amer. J. Phys. 54 (4) (1986) , 302 - 306 .
• S Drake, Galileo's 'Dialogue' : Al discreto lettore, Scientia ( Milano ) 117 (5 - 8) (1982) , 247 - 274 .
• S Drake, Alleged departures from Galileo's law of descent, Ann. of Sci. 38 (3) (1981) , 339 - 342 .
• S Drake, Ptolemy, Galileo, and scientific method, Stud. Hist. Philos. Sci. 9 (2) (1978) , 99 - 115 .
• S Drake, Galileo's experimental confirmation of horizontal inertia : unpublished manuscripts, Isis 64 (223) (1973) , 291 - 305 .
• S Drake, The evolution of 'De motu', Isis 67 (237) (1976) , 239 - 250 .
• S Drake, Velocity and Eudoxian proportion theory, Physis - Riv. Internaz. Storia Sci. 15 (1973) , 49 - 64 .
• S Drake, The uniform motion equivalent to a uniformly accelerated motion from rest, Isis 63 (216) (1972) , 28 - 38 .
• S Drake, A further reappraisal of impetus theory : Buridan, Benedetti, and Galileo, Studies in Hist. and Philos. Sci. 7 (4) (1976) , 319 - 336 .
• S Drake, Galileo's work on free fall in 1604 , Physis - Riv. Internaz. Storia Sci. 16 (4) (1974) , 309 - 322 .
• S Drake, Mathematics and discovery in Galileo's physics, Historia Math. 1 (1974) , 129 - 150 .
• S Drake, On the probable order of Galileo's notes on motion, Physis - Riv. Internaz. Storia Sci. 14 (1) (1972) , 55 - 68 .
• S Drake, Galileo's 'Platonic' cosmogony and Kepler's 'Prodromus', J. Hist. Astronom. 4 (3) (1973) , 174 - 191 .
• S Drake, The question of circular inertia, Physis - Riv. Internaz. Storia Sci. 10 (1968) , 282 - 298 .
• P Dupont, Continuità e velocità in Galileo ( Italian ) , Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 39 (1965) , 255 - 262 .
• H Erlichson, Galileo and high tower experiments, Centaurus 36 (1) (1993) , 33 - 45 .
• H Erlichson, Galileo's pendulums and planes, Ann. of Sci. 51 (3) (1994) , 263 - 272 .
• V A Fabrikant, How the concept of acceleration took shape in the mechanics of Galileo, Soviet Phys. Uspekhi 34 (2) (1991) , 201 .
• M Fehér, Galileo and the demonstrative ideal of science, Stud. Hist. Philos. Sci. 13 (2) (1982) , 87 - 110 .
• E Festa, La notion d''agrégat d'indivisibles' dans la constitution de la cinématique galiléenne : Cavalieri, Galilée, Torricelli, Rev. Histoire Sci. 45 (2 - 3) (1992) , 307 - 336 .
• M A Finocchiaro, Methodological aspects of Galileo's thought, Theoria Hist. Sci. 2 (1992) , 80 - 91 .
• M A Finocchiaro, Galileo's philosophy of science. II, A case study of interdisciplinary synthesis. With an Italian translation, Scientia ( Milano ) 112 (1 - 4) (1977) , 371 - 399 .
• M A Finocchiaro, Galileo's philosophy of science. I, A case study of the role of judgment and of philosophizing in science, Scientia ( Milano ) 112 (1 - 4) (1977) , 95 - 138 .
• M A Finocchiaro, Galileo's space-proportionality argument : a role for logic in historiography, Physis - Riv. Internaz. Storia Sci. 15 (1973) , 65 - 72 .
• M A Finocchiaro, Vires acquirit eundo : the passage where Galileo renounces space-acceleration and causal investigation, Physis - Riv. Internaz. Storia Sci. 14 (2) (1972) , 125 - 145 .
• M A Finocchiaro, Galileo as a logician, Physis - Riv. Internaz. Storia. Sci. 16 (2) (1974) , 129 - 148 .
• H R Frankel, The importance of Galileo's nontelescopic observations concerning the size of the fixed stars, Isis 69 (246) (1978) , 77 - 82 .
• R Fredette, Galileo's 'De Motu antiquiora', Physis - Riv. Internaz. Storia Sci. 14 (4) (1972) , 321 - 348 .
• M Galli, Sui contributi di Galileo alla fondazione della dinamica, Boll. Un. Mat. Ital. (3) 9 (1954) , 289 - 300 .
• M Galli, Le prove meccaniche della rotazione terrestre secondo Galileo, Boll. Un. Mat. Ital. (3) 8 (1953) , 328 - 336 .
• J Gapaillard, Galilée et le principe du chasseur, Rev. Histoire Sci. 45 (2 - 3) (1992) , 281 - 306 .
• J Gapaillard, Galilée et l'accélération de la pesanteur, Physis Riv. Internaz. Storia Sci. ( N.S. ) 29 (2) (1992) , 319 - 374 .
• E Garcia de Zuniga, Galileo and pure mathematics ( Spanish ) , Publ. Inst. Mat. Univ. Nac. Litoral 5 (1945) , 171 - 174 .
• E Garin, Galileo : the scandals of the new 'philosophy' ( Italian ) , Nuncius Ann. Storia Sci. 8 (2) (1993) , 417 - 430 .
• O Gingerich, How Galileo changed the rules of science, Sky and Telescope 85 (1993) , 32 - 36 .
• E Giusti, The philosopher-geometer. Mathematics and natural philosophy in Galileo ( Italian ) , Nuncius Ann. Storia Sci. 9 (2) (1994) , 485 - 498 .
• E Giusti, Galileo studies : the treatise 'De motu aequabili' as a model of the theory of proportions ( Italian ) , Boll. Storia Sci. Mat. 6 (2) (1986) , 89 - 108 .
• W K Goosens, Galileo's response to the tower argument, Stud. Hist. Philos. Sci. 11 (3) (1980) , 215 - 227 .
• M J Gorman, A matter of faith? Christoph Scheiner, Jesuit censorship, and the trial of Galileo, Perspect. Sci. 4 (3) (1996) , 283 - 320 .
• A T Grigorian, Measure, proportion and mathematical structure of Galileo's mechanics, in Nature mathematized I ( Dordrecht-Boston, Mass., 1983) , 61 - 65 .
• A T Grigorian, Measure, proportion and mathematical structure of Galileo's mechanics, Organon 7 (1970) , 285 - 289 .
• E G Grishko, Galileo Galilei's 'Two books' ( Russian ) , Istor.-Astronom. Issled. 21 (1989) , 144 - 154 .
• E Grosholz, Descartes and Galileo : the quantification of time and force, in Mathématiques et philosophie de l'antiquité à l'âge classique ( Paris, 1991) , 197 - 215 .
• D Gruender, Galileo and the methods of science, in Proceedings of the 1978 Pisa Conference on the History and Philosophy of Science I ( Dordrecht- Boston, Mass., 1981) , 259 - 270 .
• F Halbwachs and A Torunczyk, On Galileo's writings on mechanics : an attempt at a semantic analysis of Viviani's scholium, Synthese 62 (3) (1985) , 459 - 484 .
• A Hald, Galileo's statistical analysis of astronomical observations, Internat. Statist. Rev. 54 (2) (1986) , 211 - 220 .
• W Hartner, Galileo's contribution to astronomy, in Vistas in astronomy 11 ( Oxford, 1969) , 31 - 43 .
• D K Hill, Pendulums and planes : what Galileo didn't publish, Nuncius Ann. Storia Sci. 9 (2) (1994) , 499 - 515 .
• D K Hill, Dissecting trajectories. Galileo's early experiments on projectile motion and the law of fall, Isis 79 (299) (1988) , 646 - 668 .
• D K Hill, Galileo's work on 116 v : a new analysis, Isis 77 (287) (1986) , 283 - 291 .
• D K Hill, The projection argument in Galileo and Copernicus : rhetorical strategy in the defence of the new system, Ann. of Sci. 41 (2) (1984) , 109 - 133 .
• K Hutchison, Sunspots, Galileo, and the orbit of the Earth, Isis 81 (306) (1990) , 68 - 74 .
• M de Icaza Herrera, Galileo, Bernoulli, Leibniz and Newton around the brachistochrone problem, Rev. Mexicana Fis. 40 (3) (1994) , 459 - 475 .
• S Ito, On the origin of Galileo's 'nuove scienze', Ann. Japan Assoc. Philos. Sci. 2 (5) (1965) , 243 - 252 .
• J-L Gautero and P Souffrin, Note sur la démonstration 'mécanique' du théorème de l'isochronisme des cordes du cercle dans les 'Discorsi' de Galilée, Rev. Histoire Sci. 45 (2 - 3) (1992) , 269 - 280 .
• N Jardine, Galileo's road to truth and the demonstrative regress, Studies in Hist. and Philos. Sci. 7 (4) (1976) , 277 - 318 .
• R Lehti, The complete sphere and the complete grasshopper : gleams of Galileo Galilei's mathematical metaphysics and epistemology ( Finnish ) , Arkhimedes 37 (2) (1985) , 94 - 112 .
• W L Maar, Galileo and dialectics : synthesis through the experiment and nature as the domain of objects ( Portuguese ) , Cad. Hist. Filos. Cienc. (3) 3 (1 - 2) (1993) , 11 - 65 .
• C Maccagni, Galileo, Castelli, Torricelli and others - The Italian school of hydraulics in the 16 th and 17 th centuries, in G Garbrecht ( ed. ) , Hydraulics and Hydraulic Research: A Historical Review ( Rotterdam-Boston, 1987) , 81 - 88 .
• J MacLachlan, Galileo's experiments with pendulums : real and imaginary, Ann. of Sci. 33 (2) (1976) , 173 - 185 .
• Q Majorana, Obituary : Galileo Galilei, Rend. Sess. Accad. Sci. Ist. Bologna ( N.S. ) 46 (1942) , 92 - 117 .
• H Margolis, Tycho's system and Galileo's 'Dialogue', Stud. Hist. Philos. Sci. 22 (2) (1991) , 259 - 275 .
• S Mas Torres, Mathematics, engineering and instruments in the work of Galileo ( Spanish ) , Teorema 13 (1 - 2) (1983) , 93 - 107 .
• D W Mertz, The concept of structure in Galileo : its role in the methods of proportionality and ex suppositione as applied to the tides, Stud. Hist. Philos. Sci. 13 (2) (1982) , 111 - 131 .
• D W Mertz, On Galileo's method of causal proportionality, Stud. Hist. Philos. Sci. 11 (3) (1980) , 229 - 242 .
• E Meyer, Galileo's cosmogonical calculations, Isis 80 (303) (1989) , 456 - 468 .
• P D Napolitani, The geometrization of physical reality : specific gravity in Ghetaldi and Galileo ( Italian ) , Boll. Storia Sci. Mat. 8 (2) (1988) , 139 - 237 .
• A Nardi, The quadrature of velocity : Galileo, Mersenne, the tradition ( Italian ) , Nuncius Ann. Storia Sci. 3 (2) (1988) , 27 - 64 .
• R H Naylor, Galileo's method of analysis and synthesis, Isis 81 (309) (1990) , 695 - 707 .
• R H Naylor, Galileo's theory of projectile motion, Isis 71 (259) (1980) , 550 - 570 .
• R H Naylor, The role of experiment in Galileo's early work on the law of fall, Ann. of Sci. 37 (4) (1980) , 363 - 378 .
• R Naylor, Galileo : real experiment and didactic demonstration, Isis 67 (238) (1976) , 398 - 419 .
• R H Naylor, Galileo's theory of motion : processes of conceptual change in the period 1604 - 1610 , Ann. of Sci. 34 (4) (1977) , 365 - 392 .
• R H Naylor, Galileo and the problem of free fall, British J. Hist. Sci. 7 (1974) , 105 - 134 .
• R H Naylor, Galileo : the search for the parabolic trajectory, Ann. of Sci. 33 (2) (1976) , 153 - 172 .
• R Naylor, The evolution of an experiment : Guidobaldo del Monte and Galileo's 'Discorsi' demonstration of the parabolic trajectory, Physis - Riv. Internaz, Storia Sci. 16 (4) (1974) , 323 - 346 .
• R Naylor, Galileo's simple pendulum, Physis 16 (1974) , 23 - 46 .
• Y Ogawa, Galileo's work on free fall at Padua : Some remarks on Drake's interpretation, Historia Sci. 37 (1989) , 31 - 49 .
• M J Osler, Galileo, motion, and essences, Isis 64 (1973) , 504 - 509 .
• P-N Mayaud, Une 'nouvelle' affaire Galilée?, Rev. Histoire Sci. 45 (2 - 3) (1992) , 161 - 230 .
• O Pedersen, Galileo and the Council of Trent : the Galileo affair revisited, Journal for the history of astronomy 14 (4) (1983) , 1 - 29 .
• J Pitt, The heavens and earth : Bellarmine and Galileo, in Revolution and continuity ( Washington, DC, 1991) , 131 - 142 .
• B Pizzorno, Investigation of Galileo's logical processes ( Italian ) , Physis - Riv. Internaz. Storia Sci. 21 (1 - 4) (1979) , 71 - 102 .
• B Pizzorno, Some logical aspects of the drama of Galileo ( Italian ) , Physis - Riv. Internaz. Storia Sci. 20 (1 - 4) (1978) , 271 - 283 .
• A Postl, Correspondence between Kepler and Galileo, Vistas Astronom. 21 (4) (1977) , 325 - 330 .
• G Prudovsky, The confirmation of the superposition principle : on the role of a constructive thought experiment in Galileo's 'Discorsi', Stud. Hist. Philos. Sci. 20 (4) (1989) , 453 - 468 .
• T Quagliariello, A clarification based on the correspondence of Galileo Galilei and Fulgenzio Micanzio ( Italian ) , Rend. Accad. Sci. Fis. Mat. Napoli (4) 62 (1995) , 63 - 72 .
• S Quan, Galileo and the theorem of Pythagoras, Ann. of Sci. 31 (1974) , 227 - 261 .
• S Quan, Galileo and the problem of concentric circles : A refutation, and the solution, Ann. of Sci. 24 (1968) , 313 - 338 .
• J Renn, Galileo's manuscripts on mechanics, Nuncius Ann. Storia Sci. 3 (1) (1988) , 193 - 241 .
• G Righini, Sulla costruzione del compasso geometrico e militare di Galileo ( Italian ) , Physis - Riv. Internaz. Storia Sci. 16 (3) (1974) , 201 - 222 .
• M L Righini Bonelli, Galileo, l'orologio, il giovilabio, Physis - Riv. Internaz. Storia Sci. 13 (4) (1971) , 412 - 420 .
• J J Roche, Harriot, Galileo, and Jupiter's satellites, Arch. Internat. Hist. Sci. 32 (108) (1982) , 9 - 51 .
• A Romana, The astronomical work of Galileo Galilei ( Spanish ) , Revista Mat. Hisp.-Amer. (4) 2 (1942) , 125 - 178 .
• C B Schmitt, The faculty of arts at Pisa at the time of Galileo, Physis - Riv. Internaz. Storia Sci. 14 (3) (1972) , 243 - 272 .
• M Segre, Galileo, Viviani and the tower of Pisa, Stud. Hist. Philos. Sci. 20 (4) (1989) , 435 - 451 .
• M Segre, Viviani's life of Galileo, Isis 80 (302) (1989) , 207 - 231 .
• M Segre, Galileo as a politician, Sudhoffs Arch. 72 (1) (1988) , 69 - 82 .
• M Segre, The role of experiment in Galileo's physics, Arch. Hist. Exact Sci. 23 (3) (1980 / 81) , 227 - 252 .
• F Selleri, Galileo and the falsification of Ptolemaic cosmology ( Italian ) , Rend. Accad. Naz. Sci. XL Mem. Sci. Fis. Natur. (5) 14 (2) (1990) , 37 - 52 .
• W R Shea, Galileo, Scheiner and the interpretation of sunspots, Isis 61 (1970) , 498 - 519 .
• W R Shea, Galileo and the justification of experiments, in Historical and philosophical dimensions of logic, methodology and philosophy of science IV ( Dordrecht, 1977) , 81 - 92 .
• A M Smith, Galileo's proof for the Earth's motion from the movement of sunspots, Isis 76 (284) (1985) , 543 - 551 .
• C Solis Santos, Rhetoric and geometry : Galileo, the Jesuits, and comets ( Spanish ) , Mathesis 9 (2) (1993) , 179 - 207 .
• K Takahashi, Galileo's labyrinth : his struggle for finding a way out of his erroneous law of natural fall. II, Historia Sci. (2) 3 (1) (1993) , 1 - 34 .
• K Takahashi, Galileo's labyrinth : his struggle for finding a way out of his erroneous law of natural fall. I, Historia Sci. (2) 2 (3) (1993) , 169 - 202 .
• J C R Vasconcelos, A theorem on inertia and the concept of speed in Galileo's 'Discourses' ( Portuguese ) , Cad. Hist. Filos. Ciênc. (3) 3 (1 - 2) (1993) , 67 - 83 .
• C Vilain, La loi galiléenne et la dynamique de Huygens, Rev. Histoire Math. 2 (1) (1996) , 95 - 117 .
• O U Vonwiller, Galileo and Newton : their times and ours, J. Proc. Roy. Soc. New South Wales 76 (1943) , 316 - 328 .
• R S Westfall, The trial of Galileo : Bellarmino, Galileo, and the clash of two worlds, J. Hist. Astronom. 20 (1) (1989) , 1 - 23 .
• R S Westfall, Science and patronage : Galileo and the telescope, Isis 76 (281) (1985) , 11 - 30 .
• E A Whitaker, Galileo's lunar observations and the dating of the composition of 'Sidereus Nuncius', Journal for the history of astronomy 9 (1978) , 155 - 169 .
• M G Winkler, and A Van Helden, Representing the heavens : Galileo and visual astronomy, Isis 83 (2) (1992) , 195 - 217 .
• W L Wisan, Galileo and the emergence of a new scientific style, in Proceedings of the 1978 Pisa Conference on the History and Philosophy of Science I ( Dordrecht- Boston, Mass., 1981) , 311 - 339 .
• W L Wisan, The new science of motion : a study of Galileo's 'De motu locali', Arch. History Exact Sci. 13 (1974) , 103 - 306 .
• W L Wisan, Galileo and God's creation, Isis 77 (288) (1986) , 473 - 486 .
• W L Wisan, Galileo and the process of scientific creation, Isis 75 (277) (1984) , 269 - 286 .

Additional Resources ( show )

Other pages about Galileo Galilei:

• Preface to Letters from Galileo
• Galileo's Confession
• Galileo's Dialogue
• The title page from Discorsi (1638)
• ... and another page
• ... and yet another page
• Multiple entries in The Mathematical Gazetteer of the British Isles ,
• Astronomy: The Dynamics of the Solar System
• Astronomy: The Structure of the Solar System
• Anstruther Solar System model
• Sci Hi blog
• Miller's postage stamps
• Heinz Klaus Strick biography

Other websites about Galileo Galilei:

• Dictionary of Scientific Biography
• Encyclopaedia Britannica
• Science Museum Florence
• The Galileo Project
• Michael Fowler ( Dialogue concerning two new sciences )
• The Catholic Encyclopedia
• Sci Hi blog ( Jupiter's moons )
• Sci Hi blog ( Galileo's telescope )
• Internet Encyclopedia of Philosophy
• Openculture ( Galileo's so-called "moon drawings" )
• MathSciNet Author profile

Honours ( show )

Honours awarded to Galileo Galilei

• Lunar features Crater Galilaei and Rima Galilaei
• Paris street names Rue Galilée ( = Galileo ) (16 th Arrondissement )
• Popular biographies list Number 9

Cross-references ( show )

• History Topics: A brief history of cosmology
• History Topics: A history of time: Classical time
• History Topics: An overview of the history of mathematics
• History Topics: Christianity and the Mathematical Sciences - the Heliocentric Hypothesis
• History Topics: Galileo's Difesa
• History Topics: General relativity
• History Topics: Infinity
• History Topics: Kepler's Planetary Laws
• History Topics: Light through the ages: Ancient Greece to Maxwell
• History Topics: Longitude and the Académie Royale
• History Topics: Mathematical discovery of planets
• History Topics: Mathematics and the physical world
• History Topics: Science in the 17 th century: From Europe to St Andrews
• History Topics: The Size of the Universe
• History Topics: The brachistochrone problem
• History Topics: The function concept
• History Topics: The mathematician and the forger
• History Topics: Theories of gravitation
• History Topics: Thomas Harriot's manuscripts
• History Topics: Weather forecasting
• Famous Curves: Catenary
• Famous Curves: Cycloid
• Famous Curves: Parabola
• Societies: Lincei Accademia
• Societies: Paris Academy of Sciences
• Other: 17th December
• Other: 1908 ICM - Rome
• Other: 1924 ICM - Toronto
• Other: 1928 ICM - Bologna
• Other: 1950 ICM - Cambridge USA
• Other: 2009 Most popular biographies
• Other: 20th January
• Other: 21st February
• Other: 22nd June
• Other: 25th July
• Other: 28th December
• Other: 31st October
• Other: 5th March
• Other: 7th January
• Other: Earliest Known Uses of Some of the Words of Mathematics (C)
• Other: Earliest Known Uses of Some of the Words of Mathematics (Q)
• Other: Earliest Uses of Symbols for Fractions
• Other: Jeff Miller's postage stamps
• Other: London Learned Societies
• Other: London Museums
• Other: London Scientific Institutions
• Other: London individuals H-M
• Other: Most popular biographies – 2024
• Other: Other London Institutions outside the centre
• Other: Oxford Institutions and Colleges
• Other: Popular biographies 2018
• Other: The Dynamics of the Solar System
• Other: The Structure of the Solar System

Subscribe or renew today

Every print subscription comes with full digital access

Science News

A new galileo biography draws parallels to today’s science denialism.

Galileo and the Science Deniers delivers a fresh assessment of the life of a scientific legend

After publishing a book describing Copernicus’ idea that the sun is at the center of the solar system, Galileo stood trial on suspicions of heresy, as depicted in this 19th century painting.

Joseph Nicolas Robert-Fleury/Alamy Stock Photo

Share this:

By Tom Siegfried

August 11, 2020 at 8:00 am

Galileo and the Science Deniers Mario Livio Simon & Schuster, $28

In basketball, legends are often known by first name alone: LeBron, Kobe, Michael. Same with entertainers: Madonna, Cher, Beyoncé.

But lists of scientific legends almost always include surnames, never just Isaac or Albert or Charles. Among the titans of modern scientific lore, only one is generally referred to exclusively by a first name: Galileo.

The man had a last name: Galilei. But fewer people know his surname than know he was one of the primary founders of modern science. Galileo merged mathematics with natural philosophy and quantitative experimental methodology to provide a foundation for understanding nature on nature’s terms, rather than Aristotle’s.

Galileo’s life has been well-documented. Dozens of biographies have been written about him since the first by Vincenzo Viviani, published in 1717 (but composed before Thomas Salusbury’s English language Galileo biography of 1664). As recently as 2010, two major scholarly biographies (by David Wootton and John Heilbron) analyzed Galileo’s life and science in great depth.

But with the lives of legends, there is always a license to produce yet another interpretation. In Galileo and the Science Deniers , astrophysicist Mario Livio has invoked that license to tell Galileo’s story once more, this time with a particular concern for Galileo’s relevance to science today (and the impediments to its acceptance). “In a world of governmental antiscience attitudes with science deniers at key positions,” Livio writes, “Galileo’s tale serves … as a potent reminder of the importance of freedom of thought.”

Sign Up For the Latest from Science News

Headlines and summaries of the latest Science News articles, delivered to your inbox

Thank you for signing up!

There was a problem signing you up.

Livio also set out to produce a biography more accessible to a general reader than the typical scholarly tomes. And he succeeded. His commentaries comparing Galileo’s time to today’s are weaved into an engagingly composed and pleasantly readable account.

In Livio’s view, today’s deniers of climate change science or the validity of evolutionary theory are comparable to the religious opponents of Galileo’s scientific views, particularly his insistence on the motion of the Earth around the sun. Serving that end, the book is not an in-depth biography as much as a summary of Galileo’s life and science, plus a thorough recounting of the events leading up to his famous trial. Livio plays the role of a highly capable legal commentator in analyzing the issues raised during the trial, including discussion of the questionable tactics by the prosecution and Galileo’s not always effective defense.

Galileo’s trial centered on his book Dialogue Concerning the Two Chief World Systems , in which three characters discuss the pros and cons of the Aristotelian cosmos, with Earth at the center, and the sun-centered solar system advocated by Copernicus. Galileo thought his book had been approved by the proper censors. But his enemies orchestrated heresy charges. Galileo’s book, the prosecution alleged, defied a Catholic Church order in 1616 forbidding him from advocating Copernicanism. Galileo’s argument that his book merely described the opposing views without affirming either side was rejected; he was convicted and sentenced to house arrest for the rest of his life.

Livio’s account of this well-known story is enhanced by insights drawn from more recent scholarship, including the discovery in 1998 of a letter written during the trial suggesting that a plea bargain might have been considered. Of particular interest is Livio’s account of a Galileo biography written by Pio Paschini, commissioned in the 1940s by the Pontifical Academy of Sciences, supposedly to explain how the Catholic Church had not really persecuted Galileo, but helped him. Instead, Paschini’s manuscript told the truth, so the church refused to publish it. In the 1960s, after Paschini’s death, the church relented, authorizing publication — but only after revisions that bowdlerized the original version to portray the church in a more favorable light.

Today, of course, science and religion still encounter tensions. But most recently, opposition to science has emerged as a more general public attitude, driven most prominently by climate science deniers and antivaccine propagandists. At times, Livio’s comparisons of such movements to opposition to Galileo seem a bit of a stretch. But in its essence, his point is on target. In particular, he assails a common misinterpretation of the Galileo lesson: that the minority view should be considered correct. Some climate change deniers, Livio notes, argue that the majority opposed Galileo, even though he turned out to be right; therefore minority views on climate change, though mocked by the majority, will also turn out to be right. But such reasoning is deeply flawed. “Galileo was right not because he had been mocked and criticized but because the scientific evidence was on his side,” Livio rightly declares.

As Paschini had written in his censored manuscript, Galileo presented a fair account of the scientific evidence for the Aristotelian and Copernican views of the universe. Paschini argued, as Livio notes, that “it wasn’t Galileo’s fault … that Copernicanism appeared much stronger.” Then as now, some scientific cases are stronger than others. Sadly, now as then, the stronger scientific case does not always sway the policy of the authorities — as the U.S. government’s response to the current pandemic illustrates. In the end, Galileo’s case was strong enough to survive. So his story is worth retelling.

Buy Galileo and the Science Deniers from Amazon.com .  Science News  is a participant in the Amazon Services LLC Associates Program. Please see our  FAQ  for more details.

More Stories from Science News on Science & Society

Online spaces may intensify teens’ uncertainty in social interactions

Want to see butterflies in your backyard? Try doing less yardwork

Ximena Velez-Liendo is saving Andean bears with honey

‘Flavorama’ guides readers through the complex landscape of flavor

Rain Bosworth studies how deaf children experience the world

Separating science fact from fiction in Netflix’s ‘3 Body Problem’ 

Language models may miss signs of depression in Black people’s Facebook posts

Aimee Grant investigates the needs of autistic people

Subscribers, enter your e-mail address for full access to the Science News archives and digital editions.

Not a subscriber? Become one now .

More From Forbes

30 great biographies to bury yourself in.

• Share to Facebook
• Share to Twitter
• Share to Linkedin

Jonathan Eig's "King: A Life," a biography of civil rights leader Martin Luther King Jr., was ... [+] recognized as one of the best books of 2023.

Biographies offer a chance to explore the decision-making and circumstances around some of history’s most fascinating events. The best biography books offer fresh insights into familiar situations that you may have learned about in history class but never explored in-depth. You can learn the unexpected reasoning behind why a president went with option A instead of option B, or how a scientist’s early failures led to a groundbreaking discovery. Biographies often chronicle the lives of famous people, but sometimes they focus on people who never attained celebrity status despite doing extraordinary things. This list of the top biographies includes people of all backgrounds who can teach us things about life, passion, perseverance and more.

Top Biography Books

Biographies are different from autobiographies. A biography is an account of someone’s life written by someone else. An autobiography is an account of someone’s life that they write themselves. For instance, The Autobiography of Benjamin Franklin was written by the Founding Father. But more than two centuries later, Walter Isaacson wrote a biography of Benjamin Franklin.

Some of the most popular and well-known biographies include Isaacson’s recent book about Elon Musk, Ron Chernow’s Alexander Hamilton , which inspired the musical about the former Secretary of the Treasury, and The Immortal Life of Henrietta Lacks by Rebecca Skloot, about a woman who changed the course of modern medicine. The biographies on this list were selected based on critical acclaim, sales and impact on popular culture.

Cincinnati Reds great Pete Rose is the subject of one of the best biographies, a new one called ... [+] "Charlie Hustle."

30. Charlie Hustle: The Rise and Fall of Pete Rose, and the Last Glory Days of Baseball by Keith O'Brien (2024)

Sony is making a truly terrible mistake with helldivers 2 update sony reverses course, google tests much needed google photos feature upgrade, ‘baby reindeer’: stephen king writes essay praising netflix stalker series.

The newest book on the list, this New York Times bestseller chronicles the highs and lows of baseball’s all-time hits leader, who was banned from the Hall of Fame for betting on baseball. Keith O’Brien looks at FBI records and press coverage to build a comprehensive portrait of the former Cincinnati Reds star.

This book is best for sports fans who want to go beyond Xs and Os. Keith O’Brien’s Charlie Hustle is available from Penguin Random House .

29. The Woman They Could Not Silence by Kate Moore (2021)

Kate Moore ( Radium Girls ) uncovers the story of Elizabeth Packard, a woman confined to a mental asylum in the 19 th century for daring to have opinions and push back against social norms by giving a voice to other women like herself. It earned a GoodReads Choice nomination for Best History & Biography.

This book is best for history buffs looking for lesser-known stories. Kate Moore’s The Woman They Could Not Silence is available from Sourcebooks .

28. The Doctors Blackwell: How Two Pioneering Sisters Brought Medicine to Women and Women to Medicine by Janice P. Nimura (2021)

Elizabeth Blackwell became the first female physician in the United States in 1849—and perhaps more remarkably, her sister, Emily, soon became the second. This New York Times bestseller traces their journeys and the founding of the famed New York Infirmary for Indigent Women and Children, the first U.S. hospital run by women.

This book is best for anyone interested in medical history, science pioneers or sibling rivarly. Janice P. Nimura ’s The Doctors Blackwell is available from W.W. Norton .

27. Team of Rivals: The Political Genius of Abraham Lincoln by Doris Kearns Goodwin (2005)

There have been many biographies of the 16 th president, but this stands out for presenting his story based around his cabinet, which (as the title suggests) he stacked with his political enemies. Pulitzer Prize winner Doris Kearns Goodwin presents the story, which inspired Steven Spielberg ’s Oscar-winning movie Lincoln , like a fast-paced novel.

This book is best for those who enjoy the psychology of rivalries. Doris Kearns Goodwin ’s Team of Rivals is available from Simon & Schuster .

Author Doris Kearns Goodwin's Abraham Lincoln biography is one of the best reads about the 16th ... [+] president.

26. Frida: A Biography of Frida Kahlo by Hayden Herrera (2002)

Arguably the most famous Mexican woman of her (or any) generation, Frida Kahlo has inspired many with her art. This biography in turn explores her own inspirations and influences, adding greater depth to her well-known romance with Diego Rivera and other stories. The San Francisco Chronicle said the book made Kahlo “fully human.”

This book is best for those who appreciate art or want to learn more about Mexican history. Hayden Herrera ’s Frida is available from HarperCollins .

25. The Immortal Life of Henrietta Lacks by Rebecca Skloot (2001)

Young mother Henrietta Lacks died of cancer in 1951, but her “immortal cells” live on today, fueling countless medical advances. Yet her family didn’t learn of her contributions until two decades later and didn’t profit from them. Journalist Rebecca Skloot uncovers the racism and disturbing history of discrimination within medicine while telling a human story.

This book is best for anyone who watched the Oprah Winfrey film about Lacks on HBO and wants to learn more. Rebecca Skloot ’s The Immortal Life of Henrietta Lacks is available from Penguin Random House .

A painting of Henrietta Lacks hangs in the entryway of the Henrietta Lacks Community Center at Lyon ... [+] Homes in the Turner Station neighborhood of Baltimore. She is the subject of "The Immortal Life of Henrietta Lacks," one of the best biographies.

24. Becoming Dr. Seuss by Brian Jay Jones (2019)

Rhyming isn’t easy, but Dr. Seuss made it look breezy. In this comprehensive look at the former advertising man’s life, Brian Jay Jones traces Theodor Geisel’s career trajectory to political cartoonist and author, as well as discussing some of the views that have received criticism in recent years.

This book is best for anyone who ever read a Dr. Seuss book, which is everyone. Brian Jay Jones ’ Becoming Dr. Seuss is available from Penguin Random House .

23. Steve Jobs by Walter Isaacson (2011)

From his extreme diets to his trademark black turtlenecks, Steve Jobs was a man like none other, for better or worse. Esteemed biographer Walter Isaacson captures the nuance of his personality and the genius that drove him to create companies that made things people feel passionately about. The bestselling book became a 2015 movie.

This book is best for anyone who loves or hates Apple products. Walter Isaacson ’s Steve Jobs is available from Simon & Schuster .

Late Apple CEO Steve Jobs is the subject of an acclaimed biography by Walter Isaacson.

22. All the Frequent Troubles of Our Days by Rebecca Donner (2021)

This National Book Critics Circle Award for Biography made the best books of the year list for Time , The Wall Street Journal and The New York Times . It pulls back the curtain on the women who led the largest resistance groups against the Nazis in Germany, including the author’s great-great aunt.

This book is best for those looking for a new perspective on World War II. Rebecca Donner ’s All the Frequent Troubles of Our Days is available from Little, Brown & Co .

21. Redbone: The True Story of a Native American Rock Band by Christian Staebler and Sonia Paoloni, illustrated by Thibault Balahy (2020)

At what price does commercial success come? That question haunted musicians Pat and Lolly Vegas, Native American brothers who influenced stars like Jimi Hendrix and the Doors, as they rose to fame with the Redbone hit “Come and Get Your Love.” But they later shifted their focus to the American Indian Movement.

This book is best for fans of the Guardians of the Galaxy soundtrack and those looking for a different take on Native American history. Christian Staebler and Sonia Paoloni ’s Redbone is available from Penguin Random House .

20. The Vice President's Black Wife: The Untold Life of Julia Chinn by Amrita Chakrabarti Myers (2023)

Richard Mentor Johnson, vice president under Martin Van Buren, married enslaved Black woman Julia Ann Chinn. Though he refused to give her freedom, he did give her power on his estate. The relationship, which was likely not consensual, ultimately cost him his political career, and this book details how.

This book is best for fans of presidential history looking for untold stories. Amrita Chakrabarti Myers ’ The Vice President’s Black Wife is available from University of North Carolina Press .

19. Cleopatra: A Life by Stacy Schiff (2011)

Cleopatra may be the most famous woman in history, but her notoriety has overshadowed her incredible life and accomplishments. Pulitzer Prize-winning author Stacy Schiff adds depth to her story through a thoroughly researched history that also dispels misogynistic myths about the queen of Egypt.

This book is best for anyone curious about Egyptian history or who loves the classics . Stacy Schiff’s Cleopatra is available from Little, Brown & Co .

Stacy Schiff wrote an outstanding biography of Egyptian queen Cleopatra.

18. All That She Carried by Tiya Miles (2021)

This National Book Award winner and New York Times bestseller chronicles a bag passed down from an enslaved woman to future generations, which becomes the starting point for this poignant and well-researched book about the generational impact of slavery.

This book is best for everyone and should be required reading to humanize topics too often glossed over in political debates. Tiya Miles ’ All That She Carried is available from Simon & Schuster .

17. Empire of the Summer Moon: Quanah Parker and the Rise and Fall of the Comanches, the Most Powerful Indian Tribe in American History by S. C. Gwynne (2011)

Quanah Parker, the biracial son of a pioneer woman who became the last Comanche chief, battled white settlers over land in the American West for decades. The book traces both his personal story (he was undefeated in battle) and the greater implications of the stealing of tribal lands.

This book is best for those looking for new stories about the Old West. S.C. Gwynne ’s Empire of the Summer Moon is available from Simon & Schuster .

16. Becoming Nicole: The inspiring story of transgender actor-activist Nicole Maines and her extraordinary family by Amy Ellis Nutt (2016)

Nicole Maines rose to fame when she became the first transgender woman to play a superhero on TV. Chronicling her journey from adoption to getting the job on Supergirl , this Amazon Editors Pick and New York Times bestseller also shows how her family changed their views on gender identity and the impact on their community.

This book is best for fans of comic books. Amy Ellis Nutt ’s Becoming Nicole is available from Penguin Random House .

Actress Nicole Maines speaks at a "Supergirl" presentation at Comic-Con International. She's the ... [+] subject of a heralded biography.

15. Victoria: The Queen: An Intimate Biography of the Woman Who Ruled an Empire by Julia Baird (2016)

The Victoria depicted in history books is way too dry. An Esquire and New York Times pick for best book of 2016, Victoria illuminates how the future monarch went from fifth in line for the crown to a teenage queen to a mother of nine who somehow survived eight attempts on her life.

This book is best for anyone who’s ever struggled with work-life balance. Julia Baird’s Victoria is available from Penguin Random House .

14. The Three Mothers: How the Mothers of Martin Luther King, Jr., Malcolm X, and James Baldwin Shaped a Nation by Anna Malaika Tubbs (2021)

This remarkable book draws a line between the mothers of three of the most important Black men in American history, celebrating Black motherhood and shining a light on how they resisted Jim Crow while bringing up their sons. It was named one of Amazon's Best Biographies and Memoirs of 2021.

This book is best for parents and anyone interested in civil rights. Anna Malaika Tubbs ’ The Three Mothers is available from Macmillan .

13. Alexander Hamilton by Ron Chernow (2004)

Lin-Manuel Miranda was so inspired by this Founding Father biography that he famously wrote some of the music for Hamilton on his honeymoon. Pulitzer Prize winner Ron Chernow follows Alexandar Hamilton from immigration to member of George Washington’s cabinet to death in a duel with his nemesis, Aaron Burr.

This book is best for fans of the Broadway show and presidential history. Ron Chernow ’s Alexander Hamilton is available from Penguin Random House .

"Hamilton" author Ron Chernow and the cast appear onstage at the opening night curtain call for ... [+] "Hamilton" at the Pantages Theatre on August 16, 2017 in Los Angeles.

12. The Crusades of Cesar Chavez: A Biography by Miriam Pawel (2014)

Pulitzer Prize winner Miriam Pawel tells the story of one of the most influential and revered U.S. labor leaders in this National Book Critics Circle Award finalist. She doesn't cover up his flaws, but she does illustrate why he was so successful while saluting his enduring humanity.

This book is best for those looking for deep dives on labor or Latine history. Miriam Pawel ’s The Crusades of Cesar Chavez is available from Macmillan .

11. Warhol by Blake Gopnik (2020)

Andy Warhol is so famous, you only need to mention his last name for instant recognition. Art critic Blake Gopnik blends understanding of Warhol’s medium with excellent research and conclusions to paint the most complete picture yet of one of the defining artists of the 20 th century.

This book is best for pop culture devotees and fans of art history. Blake Gopnik ’s Warhol is available from HarperCollins .

10. Billion Dollar Whale: The Man Who Fooled Wall Street, Hollywood, and the World by Bradley Hope and Tom Wright (2018)

The Financial Times and Fortune tabbed this one of the best books of 2018 for telling the unlikeliest of stories: How a Malaysian MBA used Goldman Sachs and other financial institutions to steal billions of dollars he used to pay for real estate, parties—and even the making of The Wolf of Wall Street .

This book is best for Hollywood and movie lovers. Bradley Hope and Tom Wright’s Billion Dollar Whale is available from Hachette Books .

9. The Rebellious Life of Mrs. Rosa Parks by Jeanne Theoharis (2013)

There’s so much more to Rosa Parks’ story than one day on a bus in Montgomery. Jeanne Theoharis takes a comprehensive look at her six decades of activism and why she wasn’t the “accidental catalyst” the history books have made her sound like, regaining Parks her agency.

This book is best for those who know how the Montgomery Bus Boycott began but don’t know about Parks’ earlier involvement in organizing. Jeanne Theoharis’ The Rebellious Life of Mrs. Rosa Parks is available from Penguin Random House .

8. American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Kai Bird and Martin J. Sherwin (2005)

The inspiration behind Christopher Nolan ’s summer’s blockbuster film Oppenheimer won the Pulitzer Prize and hit No. 1 on the New York Times bestseller list. It tells J. Robert Oppenheimer’s life story, with a particular focus on the bomb and how it played into the Cold War.

This book is best for anyone who saw the movie and wants to know more. Kai Bird and Martin J. Sherwin’s American Prometheus is available from Penguin Random House .

"Oppenheimer" cast members Matt Damon, Emily Blunt, Cillian Murphy and Florence Pugh. The movie is ... [+] based on the prize-winning biography.

7. Self Made: The Life and Times of Madam C.J. Walker by A'Lelia Bundles (2002)

Madam C.J. Walker, her enslaved parents’ first freeborn child, became one of the wealthiest women of her time. Entirely self-made, she used wealth gained from her cosmetics empire caring for Black hair to help uplift other women and connect with civil rights leaders. The author is Walker’s great-great granddaughter.

This book is best for people obsessed with the Forbes billionaire lists. A’Lelia Bundles ’ Self Made (originally titled On Her Own Ground) is available from Simon & Schuster .

6. Three Ordinary Girls: The Remarkable Story of Three Dutch Teenagers Who Became Spies, Saboteurs, Nazi Assassins—and WWII Heroes by Tim Brady (2021)

World War II is a hugely popular literary period, and here’s another worthy biography from that era, following the Nazi resistance efforts of Dutch teens Hannie Schaft and sisters Truus and Freddie Oversteegen. They saved countless children and Jews from concentration camps and even assassinated German soldiers.

This book is best for World War II aficionados and fans of hidden history. Tim Brady’s Three Ordinary Girls is available from Kensington Books .

5. Bruce Lee: A Life by Matthew Polly (2018)

This highly rated (4.8/5 stars on Amazon) book incorporates information gleaned from more than 100 interviews, which helped Polly piece together scenes from Lee’s childhood in Hong Kong and the challenges he faced from racism in Hollywood. It also investigates his shocking and still mysterious death.

This book is best for fans of martial arts or who want to know what it was like to be Asian in Hollywood decades ago. Matthew Polly ’s Bruce Lee is available from Simon & Schuster .

Bruce Lee from the 1972 film "The Way of the Dragon." He is the subject of Matthew Polly's ... [+] biography.

4. Orwell's Roses by Rebecca Solnit (2021)

This finalist for the National Book Critics Circle Award explores author George Orwell’s career from a unique angle: looking at his passion for gardening. Rebecca Solnit ties his devotion to his plants to his work as a writer and an antifascist. It presents him in a different light than past biographies.

This book is best for gardeners and those who’ve read 1984 . Rebecca Solnit ’s Orwell’s Roses is available from Penguin Random House .

3. Billie Holiday: The Musician and the Myth by John Szwed (2015)

Billie Holiday’s story is too often simplified to a rags-to-riches tale focusing on her struggles pre- and post-fame. But her influence, accomplishments and enduring power are far too grand to tokenize. This biography focuses on her music, allowing jazz scholar John Szwed to illustrate what made her so spectacular.

This book is best for jazz and music fans. John Szwed ’s Billie Holiday is available from Penguin Random House .

2. Empire of Pain: The Secret History of the Sackler Dynasty by Patrick Radden Keefe (2023)

The Sacklers were once revered for their philanthropy, but the opioid epidemic unmasked how they sold and marketed a painkiller that catalyzed the crisis. This New York Times bestseller traces three generations of the family and their insistence on downplaying the addictiveness of opioids. It asks and answers how they avoided accountability.

This book is best for fans of Hulu’s Dopesick and anyone looking for more information about the opioid crisis. Patrick Radden Keefe ’s Empire of Pain is available from Penguin Random House .

Tufts employee Gabe Ryan removes letters from signage featuring the Sackler family name at the Tufts ... [+] building. The biography "Empire of Pain" details what led to the Sacklers' fall from grace.

1. King: A Life by Jonathan Eig (2023)

Hailed by the New Yorker , Washington Post , Time and Chicago Tribune as one of the best books of 2023, King is a definitive biography of civil rights leader Martin Luther King Jr. It’s also the first to rely on recently declassified FBI files, giving greater depth to the narrative and this unique American story.

This book is best for those who want to go beyond the “I Have a Dream” speech. Jonathan Eig ’s King is available from Macmillan .

What Are The Most Entertaining Biographies?

The most entertaining biographies will teach lessons and impart wisdom while also keeping you on the edge of your seat, anticipating the next development in a storied life. Famed pop culture figures and entertainers make great subjects. 

For an in-depth and fast-paced look at one of our most celebrated jurists, check out 2018’s  Ruth Bader Ginsburg: A Life by Jane Sherron de Hart. If you want laughs and a behind-the-scenes peek at a seminal variety show, try David Bianculli’s 2010 book The Uncensored Story of 'The Smothers Brothers Comedy Hour . And to lose yourself in a dishy, reads-like-a-novel bio of the ultimate girlboss, try Marisa Meltzer’s 2023 Glossy: Ambition, Beauty, and the Inside Story of Emily Weiss's Glossier .

What Are The Best Professional Biographies?

The best professional biographies make connections between the habits and hopes of dreamers and their eventual success. They often provide a blueprint for success that readers can adopt for their own lives. 

To learn how to build a truly impressive empire, read Neal Gabler’s 2006  Walt Disney: The Triumph of the American Imagination . Another American legend is the subject of T.J. Stiles’ 2010 National Book Award winner The First Tycoon: The Epic Life of Cornelius Vanderbilt , which is as much about capitalism as Vanderbilt. And in 2016’s Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race , Margot Lee Shetterly shows how Black women professionals were discriminated against at NASA—but still helped land a man on the moon. 

What Are The Best Presidential Biographies?

The best presidential biographies reveal never-before-known details about famous leaders’ lives. It can be challenging to dig up something new but so rewarding because it helps our understanding of how these men governed and led. 

Arguably the best presidential biography is Robert Caro’s portrait of Lyndon B. Johnson, starting with 1990’s  The Path to Power , which traces LBJ’s journey from early childhood to the start of his political career. An enduring book is Edmund Morris’ acclaimed 1979 The Rise of Theodore Roosevelt , which paints a full picture of a complicated man. And 2017’s  The Unexpected President: The Life and Times of Chester A. Arthur by Scott S. Greenberger shows that even a long-forgotten president still has influence and value. 

Bottom Line

Biographies offer an escape into someone else’s story, giving you the chance to see why they made their decisions and second-guess them if you like. Whether you prefer biographies focused on history, pop culture or science, you can find a book you’ll love on this list.

• Editorial Standards
• Reprints & Permissions