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The world into which Galileo Galilei was born was remarkably different from our own. Music was taught as a branch of mathematics. Medical students learned astrology as an aid to diagnosis and prognosis. Ice was believed to be heavier than water. A ten-pound stone was thought to fall ten times as fast as a one-pound stone. The world was the center of the universe, and the Vatican was the center of the world.

Into this cosmos stepped a revolutionary polymath-mathematician, physicist, astronomer, inventor, philosopher, and poetwho forever transformed the way we see our universe and ourselves. Galileo clashed famously with the Catholic Church, which held that his sun-centered universe was contrary to scripture. The Holy Office of the Inquisition ultimately ordered that he be placed under perpetual house arrest and banned his book, Dialogue on the Two Chief Systems of the World, which stayed listed on the Index of Prohibited Books for two hundred years. Yet Galileo remained faithful to the Church throughout his life, entrusting his two daughters to the convent of San Matteo near Florence.

Of Galileo's three children, only his daughter Virginia mirrored his own brilliance, industry, and sensibility. Her letters to her father, lovingly preserved by him, the margins sometimes marked with Galileo's notes, calculations, and diagrams, bear witness to the powerful emotional and intellectual bond between father and daughter. Virginia, Galileo wrote, was "a woman of exquisite mind, singular goodness, and most tenderly attached to me." Her letters, many of which are published here for the first time, not only illuminate the human side of this scientific genius but also convey the texture of Renaissance Italy with remarkable immediacy.

Galileo was born in 1564 near Pisa, a city within the grand duchy of Tuscany ruled by the powerful House of Medici. His father, Vincenzio, was a poor but gifted musician whose experiments with the harmonics of pipes and strings first introduced Galileo to the experimental method. Galileo, sent to the University of Pisa to study medicine in 1581, disappointed his father by turning his attention instead to mathematics, which he saw as the key to the physical world. At Pisa, he conducted famous studies of motion, such as dropping cannonballs of different weights from the Leaning Tower to demonstrate that the heavier ball did not fall significantly faster, contrary to what Aristotelian physical theory predicted.

After making academic enemies at Pisa, Galileo left in 1592 to take a better-paying position at the more prestigious University of Padua, where his fortunes flourished. He invented a "geometric and military compass," which was quickly adopted by kings and generals across Europe as an invaluable tool for calculating the arrangement of armies on the battlefield. He also ingratiated himself with the powerful Medici family. When Galileo's telescope revealed the four moons of Jupiter in 1610, he named them after the Medici heir apparent and his three younger brothers, and dedicated his book describing these marvelous discoveries, The Starry Messenger, to the young prince.

It was also during his sojourn in Padua that Galileo met Marina Gamba, who bore him three children without ever becoming his wife. Galileo eventually legitimized their son, Vincenzio, paving the way for him to enter Galileo's own social class and become his legal heir. But, Galileo viewed his two daughters, Virginia and Livia, as unmarriageable. After Galileo gained his long-sought position as "philosopher and mathematician to the Grand Duke," Cosimo de' Medici, he began to search for a place for his daughters among the fifty-three convents of Florence.

As many as one-half of the daughters of Florence's patrician families spent some portion of their lives cloistered, although many of them eventually left the convent to marry. Galileo insisted that the two sisters stay together despite laws prohibiting the placement of natural sisters in the same convent. Perhaps he already saw in Livia the signs of melancholy that would incapacitate her intermittently throughout her life and hoped that her older sister would care for her. Eventually he did secure a space for both in the convent of San Matteo in Arcetri, about a mile south of Florence. Virginia was thirteen and Livia twelve when they first passed through the convent's gates. When she reached the age of sixteen, Virginia took her vows and the name Suor (Sister) Maria Celeste, reflecting her father's interest in the celestial spheres. A year later, Livia became Suor Arcangela.

It was about this time, in 1616, that Galileo faced his first major conflict with the Church. Just as his father had struggled against the limits of medieval polyphony and helped to pave the way for new forms in music, Galileo rebelled against the prevailing Aristotelian physics and metaphysics, arguing instead for science based on observations of the world around him. His own observations of the planets and stars led him to support the theories of Nicolaus Copernicus, who had proposed some seventy years earlier that day and night were caused by the earth's rotation, not the sun's revolution around the earth. The publication of Galileo's famous Dialogue on the Two Chief World Systems in 1632 led to his trial for heresy by the Holy Office of the Inquisition.

In 1633, the aged and infirm Galileo was summoned to Rome and chastened by the Church. Throughout this ordeal, Galileo found solace in correspondence with his elder daughter. She wrote him of the convent's most pressing needs, managed the affairs of his household when he was in Rome, and even assisted friends of his who sought to remove potentially incriminating evidence from his home. She alone among the sisters was called upon by the mother abbess to conduct the convent's correspondence, just as she was called to direct its choir and tend to its sick. Yet she found time to pray for her father and send him detailed news of home, while he grew increasingly dependent upon her for his emotional support.

Throughout Galileo's Daughter, Dava Sobel draws on a collection of 124 letters written by Suor Maria Celeste to her father. These letters, now preserved in the National Central Library of Florence, narrate an enduring story of faith and love. Sobel uses them to reanimate a forgotten woman. By Galileo's own estimation, as well as in the opinion of his friends, she was the most important person in his life. When, at the age of thirty-three, Maria Celeste met her untimely death from dysentery, Galileo wrote to a friend, "I feel immense sadness and melancholy...and continually hear my beloved daughter calling to me."

Longitude, Sobel's first book, startled the publishing world by turning the arcana of history into an international bestseller, "a book full of gems for anyone interested in history, geography, astronomy, navigation, clockmaking, andnot the least-plain old human ambition and greed" (The Philadelphia Inquirer). Galileo's Daughter likewise speaks on many levels, capturing the towering mind of the man Einstein called "the father of modern physics, indeed of modern science altogether" while allowing a glimpse of his humanity and the relationship that sustained him.



Dava Sobel is an award-winning writer and former New York Times science reporter who has contributed articles to Audobon, Discover, Life, and The New Yorker. She has also been a contributing editor to Harvard magazine, writing about scientific research and the history of science.

Ms. Sobel has maintained an interest in Galileo since childhood and, with Galileo's Daughter, fulfills her ambition to plumb the renaissance scientist's life and times, and to reveal his little-explored relationship with his daughter, Suor Maria Celeste. In researching this book, she traveled to Italy four times and translated original documents, including more than 120 letters from Suor Maria Celeste to her famed father.

Ms. Sobel's previous book, Longitude, became an international bestseller and has been translated into more than twenty foreign languages. It has won several awards, including the American Academy of Arts and Letters' Harold D. Vursell Memorial Award, Book of the Year in England, Le Prix Faubert du Coton in France, and Il Premio del Mare Circeo in Italy. Also, in recognition of Longitude, Ms. Sobel was made a fellow of the American Geographical Society.

In summer 2000, the A&E Network broadcast a four-hour miniseries dramatization of Longitude produced as a joint production of Granada Films and A&E. NOVA is currently developing a television documentary of Galileo's Daughter.

Ms. Sobel lives in East Hampton, New York.


"History comes alive as Sobel alternates the narrative on scientific discovery with lively descriptions of the society in which they were set...Galileo's Daughter is a remarkable work for the beauty of the writing and the clarity of the time and relationships it creates."Denver Post

"A fascinating history lesson disguised as family drama...Sobel is a most original writer, with a reverence for history and storytelling."USA Today

"Galileo's Daughter is most remarkable for its graceful combination of scholarly integrity and rhapsodic tone. Sobel imbues this potentially dry, academic story with the language and cadence of oral storytelling, and she gives it all the dramatic suspense that narrative demands."

"Sobel is well up to creating the kind of complex narrative necessary to sustain our interest as she deftly weaves the multicolored threads of her various tales together. The result is an entrancing historical memoir which will undoubtedly endear Galileo to many of the same readers who came to love the cantankerous Harrison in her bestselling Longitude."The Observer

"By integrating the domestic, scientific, political, and philosophical arenas, Sobel gets beneath the myth-encrusted carapace of the hero-martyr to offer us a more modern, fallible, and humane individual."Hungry Mind Review



How did you first learn of Suor Maria Celeste's letters to her father Galileo? What convinced you their relationship would be a good subject for a book?

Longitude led me to Galileo's Daughter. While studying Galileo's efforts to solve the longitude problem, I read a book that included a fragment of one of his daughter's letters. In it, she mentioned how she was struggling to fix the clock in the convent, and she asked him to help her. I was thunderstruck by the combination of surprisesthat Galileo had a daughter I'd never heard of, that she was a nun (of all things! when I'd always considered him an enemy of the Church), that this young woman in the early seventeenth century would attempt clock repair, and have such a father to write home to. I thought it was the best thing I'd ever heard. I hoped her letters might reveal new insights into Galileo's science and religion, but I couldn't be sure until I'd found and read them alland translated them from Italian into English. So first I appealed to several Galileo scholars, asking them what they thought of my idea. Several said they'd always meant to translate the letters themselves, and that the subject was not only worthy, but so emotional it would break my heart. Then I knew I couldn't miss.

What convinced you that Galileo's replies to his daughter have in fact disappeared? How much of his correspondence with others survives?

There's no doubt that they've disappeared. The question is, will they turn up again? No one has ever found any of these letters, despite repeated searching, whereas hundreds of the estimated four thousand letters that Galileo wrote to his contemporary scientists all over Europe have been retrieved and preserved. Most likely the mother abbess, who would have discovered years' worth of saved letters at Maria Celeste's death, destroyed them all. I suppose it is possible that the letters were merely misplaced, and might yet surface someday. I love the thought of that, but I don't really expect it to happen.

The letters bring to life many fascinating details about daily existence in Renaissance Italy, from the plague to gardening to folk remedies to family finances. What surprised you most about daily life in this period? About the way that Galileo and his family lived?

I was astounded to learn how much time was passed in illness, how even the well-to-do suffered repeatedly from ailments that could not be treated for lack of good medical knowledge. As for Galileo himself, it is remarkable to look at the mountain of his achievements in the light of his mysterious recurrent illness, which confined him to bed for several weeks or months every other year his entire adult life. Maria Celeste was constantly fabricating herbal remedies for his various complaints. She medicated herself, too, and even pulled her own teeth.

Why didn't Galileo marry Marina Gamba, the mother of his children? Certainly there is no talk of her or of any other woman in Galileo's life in his daughter's letters? Why do you think he never married?

Only Galileo and Marina Gamba know the whole truth here, but several obvious conditions may have ruled out wedlock, including the difference in social standing between the two of them. Galileo came from a highly respected, if not wealthy, family that had served the Tuscan government, while Marina's lineage was undistinguishedand Venetian to boot. Galileo, who planned to return to Florence as soon as possible, might have wondered how he could explain a Venetian wife at the court of the Grand Duke of Tuscany. Also, scholars of Galileo's time tended not to marry. Maria Celeste never mentions her mother because Marina had died well before the date of the first surviving letter.

Has Galileo's private life been neglected by previous biographers, and if so why?

His private life has not really been neglected by scholars, but most did not consider his daughter a worthy object of study. Her letters, though included in Galileo's complete works and published in Italy, never appeared in a complete translation in any other language. Perhaps she was forgotten because she did so much less in the world than he. But she turns out to be powerfully good in her own right, deeply interesting as a personality, and an important key to her father's complexity.

What was it like to visit the convent of San Matteo, which Suor Maria Celeste never left after the age of thirteen?

It was a little like seeing a ghost. The convent is greatly changed now, having been modernized considerably, with only a few original frescoes still visible in the halls, and inhabited by Carmelite fathers instead of nuns. I thought Maria Celeste might have been pleased to know this, as the Carmelites were her favorite order to have as father confessors. The outside grounds, rolling down hills covered with olive and almond trees, probably have not changed much since the seventeenth century. The most moving moment for me was seeing the convent from the window of Galileo's study in his own house around the corner, and realizing how close to each other they had lived.

In one letter she refers to the convent as a prison. Do you think she ever resented her confinement?

Her reference to the convent as a prison came at a time when Galileo faced a possible prison sentence in the dungeons of the Holy Office of the Inquisition. She had taken over the recitation of prayers he was supposed to repeat as part of his punishment, and she was looking to make any other sacrifice on his behalf. This sentiment inspired her comment, "Therefore had I been able to substitute myself in the rest of your punishment, most willingly would I elect a prison even straiter than this one in which I dwell, if by so doing I could set you at liberty." The rest of the time, I think she resigned herself admirably to her confinement, and appreciated the importance of her work, which involved praying for the souls of the world.

Why do you think it took the Vatican so long to reverse its condemnation of Galileo and his book? What other important works of science have been on the Catholic Church's Index of Prohibited Books? What books are listed today?

The Galileo case brims with so many tough theological questions and so many presumed conspiracies that it will probably remain a topic of interest and debate for centuries to come. The current pope, well aware that the treatment of Galileo still rankled Catholics and non-Catholics alike, called for a twenty-year reexamination of the events surrounding his trial. This led to an official 1992 statement by John Paul II, conceding that Galileo had suffered much, and decrying the division between science and faith. Unfortunately, His Holiness's efforts to put the matter in perspective attracted ridicule. Sanctions against Galileo's banned book, the Dialogue, were finally lifted in 1822, although a new edition of the Index, reflecting this change, was not published until 1835. I'm not sure I can name any other famous science books that have been listed on the Index. Charles Darwin's Origin of Species never appeared on it, nor did the works of Sigmund Freud, apparently because no one agitated to put them there. The Index itself no longer wields any power. The twentieth and final edition of it came out in 1948, and it was reduced to the status of a historical document in 1966.

How was the experience of writing this book different from that of writing your previous book, Longitude? What challenges did it pose?

The success of Longitude allowed me to devote myself full time to the writing of Galileo's Daughter. This was a luxury I had never enjoyed before. I was very glad to have the time and to take a long timefive yearsbecause the story of Galileo's Daughter required much more research. The translations alone took up the first year. One of the challenges was having had a previous success! People kept asking me if this book would be another small, short story just like Longitude. And I would answer, No, this story is an epic tragedy, and it calls for an entirely different approach.

What are you working on now?

I am writing a book about the planets of our solar system. My interest in astronomy is the theme that unites Longitude, Galileo's Daughter, and this current project.



  1. Suor Maria Celeste repeatedly asks Galileo for money in her letters, often apologetically. How does the tone and assuredness of these requests change over the course of the correspondence? Do you think Galileo was generous with his daughter? Is there any evidence that he refused any of her requests? How well did she manage his affairs when he was in Rome answering to the Holy Office of the Inquisition?
  2. How do you envision the day-to-day routine in San Matteo in the years that Galileo's daughters lived there (see especially chapter 11)? Which of its deprivations were most trying for Suor Maria Celeste and her sisters in faith? How did a woman who never left the convent become so well-versed in the affairs of the world?
  3. Under pressure from religious groups, the Kansas State Board of Education decided in 1999 to remove evolution and the big bang theory from the state-mandated curriculum. The move was opposed by a group named FLAT (Families for Learning Accurate Theories), a reference to the idea that the earth must be flat. Discuss the conflict between science and religion in Galileo's lifetime and ours. How have religious beliefs affected public policy concerning genetic engineering, cloning, and education?
  4. Galileo's correspondence with his daughter reveals the value of many items in Renaissance Florence, from wheat and wine to thread and wedding dresses to Vincenzio's monthly allowance. Which were relatively costly, which inexpensive? How did their price compare to the value of a good farm, Galileo's first salary as a math professor, his rent in Bellosguardo and Arcetri, and the cost of a private room in the convent?
  5. Why did Pope Urban VIII, once Galileo's ally, ultimately turn against him? How did external factors (the Thirty Years' War, alliances with France and Spain) affect his relationship with the scientist?
  6. Galileo seems to have suffered from hernias, gout, and glaucoma. His elder daughter was plagued by headaches and tooth decay, and the younger may well have experienced major depression. How were these medical illnesses regarded during their lifetimes? What kind of home remedies did they use? How were doctors and surgeons regarded by the public at large and by Galileo?
  7. The bubonic plague has been known for at least 3,000 years, and in the Middle Ages it depopulated entire cities. How did it touch the lives of Galileo and his family? Today plague still occurs in remote parts of Asia, Africa, South America, and even parts of the United States, but most cases can be treated with timely doses of antibiotics. What sorts of remedieschemical, herbal, and religiousdid Galileo and his daughters use to ward it off?
  8. Galileo was famously wrong in his explanation of what causes tides. He thought, in essence, that the spinning of the earth caused the waters to slosh about their basins. Why did he dismiss the observation of his contemporary Johannes Kepler that the tides were related to the movements of the moon?
  9. How do you think Galileo would react to the news that Pope John Paul II had called for a reexamination of his affair?
  10. Given the suggestion in one of Suor Maria Celeste's letters that she wrote out the final manuscript for Galileo's Dialogue, how do you imagine the two of them might have worked together? How do you think each of them expected the final product to be received?
  11. Viewed in this age of televised court cases, what did you think of the legal process of Galileo's trial?