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 poet-who 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, and-not 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.