Galileo's Daughter: A Historical Memoir of Science, Faith, and Love, by Dava Sobel, Penguin, 420 pp.; $14

The artificial barriers we have created to define academic disciplines often blind us to the hydrodynamics of human history, which is, by nature, a fluid medium. Religion, economics, politics, agriculture, art, domestic arrangements, science—every aspect of civilization constantly exerts or yields to pressure, gains or loses velocity, spurts ahead, eddies sideways, or stagnates, according to what's happening elsewhere in the river.

The artificial barriers were inevitable, of course. Even the most erudite among us cannot carry around inside their heads the great flood of human civilization. Cybernetic overload makes it difficult to remember, for example, that Galileo published his Dialogue on the Two Great World Systems, Rembrandt painted The Anatomy Lesson of Dr. Tulp, and the second folio of Shakespeare's plays appeared during the same year—1632. Or that Galileo and Shakespeare were born the same year, 1564—the year that Michelangelo died. Or that during Galileo's house arrest for his publication of the Dialogue, he was visited by luminaries no less bright or politically contrary than Thomas Hobbes and the young John Milton.

Yet that string of births, deaths, and encounters gives us a better sense than do period labels of how Time, like an ever-rolling stream, not only bears all its sons away but ceaselessly alters the contours of civilization. Handy though the terms "Renaissance" and "Enlightenment" may be, they give the unfortunate impression that history arrives in discrete chunks rather than as events so seamless we are rarely aware of their significance at the time. This is, after all, the way we experience our own lives, as a wash of contingency.

It is this sense of how historical watersheds emerge from the murky quotidian that Dava Sobel (author of Longitude) captures so deftly in Galileo's Daughter: A Historical Memoir of Science, Faith and Love. Most people are unaware that Galileo even had a daughter. In fact, he had a brace of them, as well as a son, though never a wife. Italian scholars, Sobel tells us, customarily did not marry, a cultural vestige of the Middle Ages when learning was almost entirely a monastic endeavor. Instead, when he was 35, Galileo took a mistress, Marina Gamba, who within a year gave birth to a daughter, baptized Virginia. The next year, another daughter, Livia, was born and a few years afterward, a son, Vincenzio. Galileo did not live in the same house with Marina and his children but supported them in a separate establishment, first in Padua, where he held the chair of mathematics at the university, and later in Pisa. When his own father died, Galileo became the paterfamilias, not only of his own irregular family but also for his younger brothers and sisters as well as various cousins, arranging marriages and careers for them as the need arose.

How did these familial exigencies affect the future of science and the way you and I picture the universe? Without them Galileo might have been content with his meager university stipend and thus never set up a workshop in his house to supplement his income by manufacturing and marketing his inventions. The first was a "geometric and military compass," much like the protractors long used in beginning geometry classes. His entrepreneurial appetite whetted, Galileo, upon hearing about a "spyglass" recently patented in The Hague by Hans Lipperhey, tried his hand at grinding lenses. His telescopes of steadily increasing magnitudes were soon the rage all over Europe. It was through a three-lens telescope of his own devising that Galileo observed and correctly identified the four moons of Jupiter. And when that event coincided neatly with Cosimo II de' Medici becoming Grand Duke of Tuscany, what better use could a hard-pressed scholar make of his discovery than to name the satellites the "Medician Stars"? As Galileo had hoped, Cosimo became his patron, appointing him Chief Mathematician of the University of Pisa and Philosopher and Mathematician to the Grand Duke, a lifetime sinecure.

With the telescope, Galileo changed forever our view of the universe. But while he had a remarkably clear sense of how momentous that transformation would prove, he had no idea that he himself would become an icon for scientific truth oppressed by religious ignorance. Indeed, in 1610 he had every reason to hope for the support not only of the Grand Duke but also of at least two powerful cardinals—Bellarmine and his uncle Barberini, both scholars of some distinction. Galileo was aware, of course, that Copernicus's De revolutionibus orbium coelestium was on shaky ground with the Church for positing a new cosmology that put the sun, rather than the Earth, at the center of its system. Indeed, Copernicus might well have been called before the Inquisition if he hadn't died almost as soon as the work appeared in print.

To be on the safe side, then, Galileo asked his friend Cardinal Bellarmine to submit his treatise The Starry Messenger, based on his observations of Jupiter's moons, to the Jesuit mathematicians of the Collegio Romano for their approval. They readily endorsed his data, although they reserved judgment as to his interpretation of his observations. Meanwhile, on a more mundane plane, the city fathers of Florence, impressed with Galileo's steadily increasing fame, commissioned him to find a way to cast a new bell for the town. None of the local craftsmen could understand why the wooden mold for the bell's inner surface kept rising when molten metal was poured between it and the mold for the outer surface. Taking his cue from the ancient Greek Archimedes, Galileo explained that bodies must be heavier than the volume of liquid they displace or they will float to the surface. This refuted Aristotle, who claimed objects floated when they "pierced" the skin of a liquid and escaped from it.

Such a matter may not seem relevant to either a cosmological or a theological debate, but anyone contradicting Aristotle was also assumed to be demeaning Thomas Aquinas, chief architect of official Church doctrine, who had based his theology on reasoning derived from Aristotle. Galileo had earlier discredited Aristotle by dropping cannonballs from the tower of Pisa to disprove his claim that objects of different weights fall at different speeds. The incident of the town bell occasioned a debate, staged at a state dinner, between Galileo and visiting clergymen. Cardinal Mafeo Barberini was so impressed with the astronomer's arguments that he became Galileo's champion upon returning to Rome and continued to promote his career throughout the next decade. With such powerful supporters, Galileo figured he had little to fear from his scholarly rivals or ecclesiastical adversaries. Certainly neither he nor Barberini foresaw the disaster that lay ahead for them.

Heartened by his successes, both celestial and terrestrial, Galileo continued his investigation of the heavens, writing treatises on sun spots and the stellar composition of the Milky Way. Probing the heavens was an enterprise humming with theological vibrations in the seventeenth century. Today we do not find our faith compromised by ceding the center of our planetary system to the sun or indeed in recognizing our entire galaxy as only one in an unimaginably large gravitational web. Yet in Galileo's time, most people still envisioned the heavens as a series of concentric and harmonic spheres, as in Dante's Paradiso. The curious ventured into this territory at their peril.

The Grand Duke's mother, the Dowager Grand Duchess Christina, began to feel uneasy about Galileo's claims. How, for example, could the sun have stood still during the battle of Gibeon as described in the book of Joshua unless that orb revolved about the earth rather than the other way round? Being attacked by jealous rivals or suspicious clergy was one thing, Galileo realized, but arousing the ire of your patron's mother was another matter. Thus, he wrote an open letter explaining how science and Holy Scripture could be reconciled. The Dowager, however, remained suspicious.

Indeed, Galileo's professional and ecclesiastical critics were growing more strident. A Dominican friar began preaching in Florence, condemning as heretical not only Galileo but all mathematicians who subscribed to the Copernican view. And though the friar's superior wrote the astronomer a letter of apology, yet another Dominican filed a written complaint against him with the Office of the Inquisition soon after.

At this point, it is important to distinguish between the Holy Office of the Inquisition in Rome and the Spanish Inquisition. The former performed special investigations for ecclesiastical courts under papal authority. By contrast, the Spanish Inquisition, legendary for its savagery, had operated under the secular control of Ferdinand and Isabella, the monarchs who financed Columbus's voyage of discovery. Its purpose was primarily to search out Jews and Muslims, though Protestants were later added to the list. Torquemada, the first Grand Inquisitor and instigator of the auto-da-fe, reportedly sent two thousand people to the stake. The Church's Office of the Inquisition, on the other hand, rarely imposed the death penalty, usually limiting its sentences to excommunication. In 1600, however, the year Galileo's first child was born, Giordano Bruno, a wandering ex-Dominican monk, had been burnt at the stake for using Copernican theory to support his pantheism. Within months of the Dominican's charges against him, Galileo was on his way to Rome to answer the accusations. He must have been nervous if not alarmed. Another scholar supporting the Copernican view had recently been banned, and the Congregation of the Index had suspended further publication of Copernicus's De Revolutionibus. Nevertheless, Galileo had not been mentioned in the ban, and his fears were allayed after he gained an audience with Pope Paul V, who assured him that he had permission to pursue his investigations without hindrance. Indeed, his friend Cardinal Bellarmine later sent Galileo an affidavit certifying that, while in Rome, he had neither been on trial nor condemned by the Inquisition.

Galileo's work certainly had its detractors at that time, but his benefactor, Cardinal Barberini, was not among them. In fact, as late as 1620, the cardinal sent Galileo a poem entitled "Adulatio Perniciosa," which he had composed in the astronomer's honor. What neither of them expected then was that in less than three years Barberini would become Pope Urban VIII and spend his papacy trying to control brushfires lit by the Thirty Years' War. At the time, however, not even a cloud the size of a man's hand darkened the astronomer's horizon. And despite his fascination with the stars, Galileo had any number of domestic duties to attend to as well.

Knowing his daughters would never be able to marry anyone but stablehands or peasants, Galileo finagled to have them accepted into a community of Poor Clares in the Convent of San Mateo outside of Florence when they were only thirteen and twelve, though the ordinary age for novices was sixteen. His own home was in the nearby village of Arcetri, so that, despite the girls' cloistered life, they were able to see family members fairly often. In due time the oldest daughter became Sister Maria Celeste (reflecting her father's devotion to heavenly studies) and the younger, Sister Archangela. About this time, Sr. Celeste began to write her father regularly, though the education that makes these missives both intelligent and elegant must have come during her years at home. Not many of the nuns at San Mateo were literate, and none on a par with Sr. Maria Celeste.

One hundred twenty-four of her letters survive, a testament to how valuable her father found them. His own letters to her were destroyed, possibly by fire at the convent. Though Sobel's excellent narrative has many sources, woven seamlessly together, its most intimate touches come from the details in Sr. Celeste's letters. The dutiful daughter delighted in baking special sweetmeats for her father and his friends and weaving fabrics to his specifications. The father reciprocated by interceding with ecclesiastical and government officials when the nuns were desperate to replace their assigned confessor, a priest who expected to receive certain carnal benefits for his services.

Galileo always responded promptly to his daughter's requests to help aging or ailing sisters, acting as ex-officio fundraiser for the convent among his rich and influential friends. Panniers of summer fruits from his orchard and other treats traveled by donkey from his villa to the convent. He also had any number of scientific projects in hand when Barberini became pope in 1623.

Indeed, immediately upon news of his patron's election, Galileo hurried to shift the dedication of his new manuscript, The Assayer, from the late Grand Duke to new Pope Urban VIII. Within months, he was in Rome once more for further consultation with strategic cardinals. While there, he had six audiences with his old friend, during which he was once more assured that he was free to write about the Copernican theory, with the proviso that he treat it as hypothesis and not fact. Returning to Florence, Galileo first revised a treatise about tides (whose hypothesis later proved false), then began writing Dialogue Concerning the Two Chief World Systems, the work which would later prove his undoing.

The Dialogue was composed as a conversation between three friends, one of whom (clearly a stand-in for the author) espouses a sun-centered system and is portrayed as by far the most astute of the three. By contrast, the advocate of the Ptolemaic system consistently proves himself to be a pompous dunce. The third member of the trio is largely persuaded by the arguments of Galileo's mouthpiece.

The barbed humor of the Dialogue was not calculated to endear Galileo to his rivals. Even well before it appeared in print, his opponents were already stepping up their clamor against him. Sometime during the winter of 1624-1625, an anonymous complaint was lodged against the book Galileo had recently dedicated to the new pope. The nameless accuser claimed that the atomism espoused in The Assayer rendered transubstantiation of the Eucharist a logical impossibility, thus violating church doctrine. However, after looking into the matter, the Office of the Inquisition cleared Galileo of the charge. Nor, evidently, was Urban VIII alarmed. In fact, he granted a small pension to Galileo's son the following year. True, the pontiff's increasing preoccupation with the war reduced communication between the pope and the astronomer, but at least no sign of suspicion or ill will emanated from the Vatican. Indeed, as late as 1630, just two months before Galileo completed the Dialogue, Urban VIII bestowed on him yet another small pension.

Wanting the Dialogue to be published in Rome, Galileo carried it thence early that summer to clear it with the church censors before delivering it to the publishers. The Vatican Secretary informed him that the body of the text had passed muster, though the authorities wanted some changes made in the preface and the ending, emphasizing more strongly the conjectural nature of his conclusions. Meanwhile, the Black Plague began to break out across Italy. And the founder of the press where the manuscript was to be printed was among its first victims in Rome.

Galileo, anxious to get home before plague quarantines made travel impossible, decided to go to Florence with his manuscript and have the book published there. In the spring, he received word from the Secretary of the Vatican that, while his revised preface and conclusion were still being considered in Rome, the remainder of the book should now be submitted to the local Florentine Office of the Inquisition for its approval. Owing to these obstacles, it was February of 1632 before the Dialogue finally appeared in print.

Throughout these irritating delays, Sr. Celeste wrote her father frequent encouraging letters, urging him to have a care for his health which was beginning, at 65, to decline. The plague continued to assault Florence for several summers, taking its toll among a number of the astronomer's friends. The convent, on the other hand, seemed curiously immune. From certain passages in the letters, it is clear that Galileo, in making the required revisions to the Dialogue, relied on his daughter to complete fair copies of his manuscript. Though Sr. Celeste modesty suppresses any mention of her various gifts, she obviously had a head for figures as well. These skills led Galileo eventually to entrust the administration of his affairs to her during what would prove a lengthy and alarming absence, one from which it was uncertain that he would ever return.

Out of the blue, only a few months after the publication of the Dialogue, Galileo had received notice that he was to stop its distribution immediately while the Inquisition further examined its content. This was indeed disturbing news. In October, he was summoned to Rome to appear before the Inquisition, over whose investigation of his book Urban VIII was personally presiding.

What occasioned this sudden shift in the wind issuing from the Vatican? Galileo had gone through all the proper channels, had submitted his work for ecclesiastical approval, not reluctantly but as an obedient son of the Church who recognized its authority to govern such matters. The book had received their imprimatur. What had caused its abrupt and awkward withdrawal?

No doubt the cause had its roots in the blood-soaked soil of northern Europe. Though the Thirty Years' War had not spread to Italy, the German princes were dragging practically every inch of the continent into their conflict. A religious dispute at the outset, pitting Protestants against Catholics, it devolved into a feud between the French Bourbons and the Germanic Hapsburgs. Thus Spain, determined that the Holy Roman Empire should survive, backed the imperial forces. France, though a Catholic country, saw an opportunity to weaken its rival Spain and thus supported the Protestant forces.

Since the "Holy Roman Empire" had been limited to German territory for the past two centuries, the pope had little to gain by backing the Catholic emperor. Besides, as papal legate to France early in his career, Urban VIII had held the infant Louis XIII at his baptism in Paris. He still maintained a personal attachment to that monarch. Nevertheless, Spain remained the most fiercely Catholic nation in Europe; Urban could ill afford to offend her religious sensibilities. Caught between conflicting loyalties, the pope found picking his way across this earthly minefield a more urgent task than pondering new cosmologies. (Urban's insomnia occasioned by his worries over the war caused him to order all the birds shot in the Vatican gardens, as their noise kept him from sleeping.)

When Galileo first received the summons to Rome, he pleaded ill health and asked if the Inquisition's branch office in Florence could examine him. Yet even after the Florentine delegation certified that Galileo was indeed too ill to travel, the pope rejected the petition and threatened to arrest him immediately and drag him to Rome in chains if necessary.

The rest of the story is the stuff of legend. Urban, for reasons not entirely clear, set his heart implacably against his former friend. After insisting on Galileo coming to Rome, he kept the old man, now 70, jailed in the Vatican for two weeks before allowing the case to move forward. During this time, a bargain was struck whereby Galileo agreed to plead guilty to lesser charges in exchange for a more lenient punishment. On April 30, 1633, the astronomer pled guilty to perhaps having made the Copernican case too strongly in the Dialogue and offered to emphasize in his next book that the heliocentric universe was only an unproved theory.

This concession, however, did not satisfy the pontiff. He sentenced Galileo to indefinite imprisonment. A month later Galileo was examined under threat of torture and convicted by an ecclesiastical court, although only seven of the ten cardinals signed the official sentence. In a ceremony at the Church of Santa Maria Sopra Minverva the next day, Galileo formally recanted his error in believing the earth moves around the sun. (As only two other people were in the room when he supposedly muttered under his breath the famous words "Nevertheless, it moves," and those hardly had an interest in such a remark being repeated, that part of the legend remains apocryphal.)

For a while, Galileo lived under house arrest at the Tuscan ambassador's residence. When his health improved sufficiently, he was allowed to travel to Siena, nearer home, where he was housed at the Archbishop's palace. Still, another five months went by before Galileo could return to his villa, which he was not permitted to leave for the rest of his life. When he petitioned to visit the doctor in town for a painful hernia, he was refused and informed that any further request would result in his immediate imprisonment.

Through all these trials, his daughter Sr. Celeste continued to write to him, consoling, anxious for his health and his return home, informing him of what fruits were ripening in the orchard, how winemaking was progressing. Her letters trace a narrow line, careful never to contradict outright the ecclesiastical hierarchy but praising her father both for his fortitude and intellect. These missives with their domestic news of home and their gentle spiritual counsel must have provided Galileo's chief solace during those long, painful months.

Once back home, he soon discovered that his daughter had concealed her own weakened condition. Having survived several onslaughts of the plague, Sr. Celeste succumbed to dysentery at the age of 34, only a few months after her father's return. Her death took from him not only his daughter but also his most trusted confidante and advisor. She was "a woman of exquisite intellect and surpassing goodness," he wrote in a heartbroken letter to a friend at the time.

Galileo himself lived on for another four years, dying at the age of seventy-nine. During those final years, he went blind, complaining in letters of his diminishing memory, though his intellect was as vigorous as ever. Despite the sentence that banned all his works, past or future, he wrote several more scientific treatises on subjects as various as pendulums and a means of determining longitude, all of which he managed to smuggle out of Italy to countries where they could be published. The Dialogue itself was taken by the French ambassador and eventually printed in Protestant Holland. That work remained on the Index until 1835, forbidden to Catholic readers for two hundred years, except by special dispensation. Perhaps no other single act has been so responsible for the widespread perception of the Church as the enemy of science.

Sobel is at pains to point out that, strictly speaking, "the Church" did not condemn Galileo's work, but only the Office of the Inquisition. The doctrine of papal infallibility was not actually defined until the first Vatican Council met in 1869-1870. Nevertheless, this is a distinction which will be lost on many of her readers. As indeed it was on Galileo himself, who silently voiced his rebuttal to the Inquisition in the margins of his own copy of the Dialogue (written, like the new Bibles, not in Latin but in the vernacular):

Who can doubt that it will lead to the worst disorders when minds created free by God are compelled to submit slavishly to an outside will? When we are told to deny our senses and subject them to the whim of others? When people devoid of whatsoever competence are made judges over experts and are granted authority to treat them as they please? These are the novelties which are apt to bring about the ruin of commonwealths and the subversion of the state.

Yet I find that I cannot applaud the whole of this stifled cry, understandable though it is on the part of a man so shabbily treated by a friend he had every reason to trust. Nor do I think Sr. Celeste would entirely endorse it, affectionate daughter though she was. A few of her letters contain gentle reminders to her father of pride's folly. Her regard for his spiritual welfare equaled her concern for his physical health.

And these days we have grown wary of "experts." Having so far survived the gift of nuclear energy, we now face the even knottier questions attending genetics. We have learned the kinds of dangers that inevitably attend such discoveries. No doubt the enormous expansion of knowledge, just as it brought about the division of learning into disciplines, now makes reliance on professional experts all too tempting when we are faced with difficult ethical decisions. Galileo was right to trust his senses, and that reliance changed our view of the universe irretrievably. But we have since learned that scientific experts do, in fact, need judges over them, and that the necessary qualification for that position goes beyond even scientific competence.

Virginia Stem Owens is a novelist, poet, and essayist.

NOTE: For your convenience, the following book, which was mentioned above, is available for purchase:

• Galileo's Daughter, by Dava Sobel

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