Why Was Galileo Put on Trial?
From 1610 to 1633: the Jesuit objections, the 1616 injunction, publication of the Dialogue, the trial before the Inquisition, the abjuration, and house arrest.
Why Was Galileo Put on Trial?
The trial of Galileo before the Roman Inquisition in 1633 is the most famous single episode in the long relationship between science and religion. It has been told, retold, distorted, simplified, mythologized, and used as a touchstone for two centuries of argument about the relationship between the Church and modern thought. The trial was a real event, and it did happen to a real man. The man was a devout Catholic, and the Church was a real institution with real concerns. The story is more complicated, and more interesting, than the standard image of “science versus religion” allows. This page follows the events of the trial in chronological order: Galileo’s early telescopic discoveries and the first wave of theological opposition; the 1615 denunciations; the 1616 injunction and the placing of Copernicus on the Index; the change of popes in 1623; the publication of the Dialogue in 1632; the trial and abjuration; and the house arrest in Arcetri. For the broader context of Galileo’s life, see the Galileo page. For the astronomical work that provoked the controversy, see What Did Galileo Discover With His Telescope?. The religious context is treated in more detail in the religion and the Church. The reasons Copernicanism was so controversial in the first place are surveyed in Why Was Copernicus’s Theory Controversial?.
The First Wave of Opposition (1610–1614)
The controversy had its origins in the period immediately after the publication of the Sidereus Nuncius in March 1610. The book was a sensation, and the discoveries it announced — mountains on the Moon, the moons of Jupiter, the resolution of the Milky Way — were soon confirmed by other observers. But the discoveries also raised immediate questions, both philosophical and theological. The Aristotelian philosophers at the universities objected that the heavens could not be imperfect, and that no new celestial bodies could exist. The theologians objected that the new findings, if true, seemed to undermine the scriptural picture of a perfect, unchanging cosmos. The early opposition was not, in the first instance, Catholic. It came from the Aristotelian establishment at the Italian universities, and it was, for several years, mostly an academic affair. The more serious opposition began in 1611, when Galileo visited Rome and demonstrated his telescope to a group of Jesuit mathematicians at the Collegio Romano. The Jesuits confirmed Galileo’s observations of the moons of Jupiter and the phases of Venus, but they were also careful about the cosmological implications. The Jesuits at the Collegio Romano were the most rigorous astronomers in Catholic Europe, and they would be Galileo’s most effective opponents in the years to come. In 1613, Galileo published his Letters on Sunspots, which were, in part, a defense of the Copernican theory. The book was dedicated to the new Grand Duke of Tuscany, and it included a long discussion of the relationship between science and scripture. Galileo argued that the Bible should be read “according to the manner in which it is customary for it to speak,” accommodating itself to ordinary perception, and that the natural philosopher’s job was to determine the physical truth about the world, leaving the spiritual interpretation of scripture to the theologians. The argument was, in essence, the modern view, and it was, in 1613, a controversial one.
The Denunciations of 1615
In 1614, a Dominican friar named Niccolò Lorini preached a sermon in Florence on the text “Ye men of Galilee, why stand ye gazing up into heaven?” — a clear reference to Galileo’s Copernicanism. The next year, a Carmelite friar named Paolo Antonio Foscarini published a tract arguing that Copernicanism was not contrary to scripture. Foscarini’s tract was denounced to the Roman Inquisition by a Dominican in Florence. Galileo responded with his famous “Letter to the Grand Duchess Christina” (1615), a long, careful, and very public defense of the view that scripture should be interpreted in light of scientific demonstration. The letter was widely circulated, and it provoked further denunciations. By the end of 1615, the matter had been referred to the Roman Inquisition, and Galileo was, with some reluctance, on his way to Rome to defend himself.
The 1616 Injunction
In February 1616, the Holy Office appointed a committee of eleven consultants, including several Jesuits, to examine the Copernican doctrine. On 24 February 1616, the committee unanimously found that the heliocentrism of Copernicus was philosophically “foolish and absurd” and theologically “erroneous in faith.” On 25 February, Galileo was summoned to the offices of the Inquisition and given a private injunction. The exact terms of the injunction are disputed, because the documents relating to it are not entirely consistent. According to one document, Galileo was ordered not to “hold, teach, or defend” the Copernican doctrine in any way, orally or in writing. According to another, he was told only that he could not “hold or defend” it. The distinction mattered, and would matter again in 1633. Galileo, for his part, accepted the injunction and left Rome. On 5 March 1616, the Index placed De Revolutionibus on the list of books forbidden until corrected. The corrections were, ironically, never made, because the theologians of the Sacred Congregation could not agree on what they should be. Galileo was not, in 1616, tried or condemned. He was warned.
The Eight Years of Silence (1616–1624)
For the next several years, Galileo was careful. He returned to his work on motion, on the strength of materials, and on a number of smaller projects. He did not, in public, defend the Copernican theory. He was, however, working privately. In 1619, he became involved in a controversy over the nature of comets, exchanging pamphlets with the Jesuit Orazio Grassi. In 1623, he published the Assayer, a brilliant polemic on scientific method in which he ridiculed Grassi’s arguments and the Aristotelian approach generally. The book is the first clear statement of the new scientific method in Italian prose. It does not, however, defend the Copernican theory. In August 1623, Galileo’s old friend Maffeo Barberini was elected Pope, taking the name Urban VIII. Urban had been, before his election, a sympathetic reader of Galileo’s work, and he had even written a poem praising Galileo’s telescopic discoveries. In 1624 Galileo visited Rome and was received by the Pope in six long audiences. The Pope is reported to have told Galileo that he should write about Copernicanism, but only as a hypothesis, not as physical truth. Galileo took this as permission to proceed, and he began work on what would become the Dialogue Concerning the Two Chief World Systems.
The Dialogue of 1632
The Dialogue took Galileo seven years to write. It was published in Florence in February 1632, in Italian, in a printing of about a thousand copies. The book was a four-day conversation among three characters: Salviati, a Copernican; Sagredo, an intelligent layman; and Simplicio, a defender of the Ptolemaic system. The book was a brilliant exposition of the case for the Copernican theory, written in a clear, vigorous Italian that reached an audience well beyond the universities. The book was, however, a political disaster. The character of Simplicio, the loser of every argument, was widely understood to be a caricature of the Pope himself. (The name “Simplicio” was the name of a sixth-century Aristotelian commentator, and the pun may not have been intentional, but it did not help.) The book also did not present the Copernican theory as a hypothesis, as the Pope had suggested. It presented it as true. The Dialogue was read eagerly in Rome, and the Pope was furious.
The Trial (1633)
In September 1632, the Pope appointed a special commission to examine the Dialogue. The commission reported in July 1633 that the book was a clear defense of the Copernican theory, in violation of the 1616 injunction. Galileo was summoned to appear before the Inquisition in Rome. He arrived in February 1633, in poor health (he had been ill for several years, and the journey in the winter weather had made him worse), and was interrogated over the course of several months. Galileo defended himself on three grounds. First, he argued that the 1616 injunction had forbidden him only to “hold or defend” the Copernican doctrine, not to discuss it as a hypothesis. The Dialogue, he said, did not defend the Copernican theory; it presented it as a hypothesis. Second, he argued that the character of Simplicio was not a caricature of the Pope but a traditional character from the Aristotelian tradition. Third, he argued that he had acted in good faith, and that the parts of the book that the commission had found most offensive had been approved by the Florentine censor. The defense did not succeed. The Inquisition was not persuaded. On 22 June 1633, Galileo founded “vehemently suspect of heresy” and was forced to recite an abjuration, declaring that he “abjured, cursed, and detested” the Copernican doctrine. The abjuration was a humiliating document, and Galileo, by all accounts, was humiliated in reciting it. The famous words “and yet it moves” — E pur si muove — are almost certainly apocryphal; they do not appear in any contemporary record, and they are not the kind of thing a man in Galileo’s position would have risked saying. The story is a piece of nineteenth-century folklore. Galileo was sentenced to formal imprisonment, immediately commuted to house arrest, first at the Medici embassy in Rome and then at his villa in Arcetri, near Florence. He was also required to recite the seven penitential psalms once a week for three years. The Dialogue placedd on the Index, and the order to “correct” De Revolutionibus was renewed.
House Arrest in Arcetri (1633–1642)
Galileo spent the last nine years of his life under house arrest in Arcetri. He was, comfortable; he had a devoted daughter, Maria Celeste, who was a nun in a nearby convent, and he was visited by friends, students, and curious foreign visitors. He was also, in difficult circumstances. He was forbidden to publish, and the Florentine censor was instructed to keep an eye on his work. His daughter died in 1634, and he was grief-stricken. In 1638, Galileo published the Two New Sciences, the masterwork of his physics, in Leiden in the Dutch Republic. The book was published without a license, because Galileo could not get one in Italy. The Two New Sciences was the more important of his two major works: it laid the foundations of the science of motion and the science of strength of materials. The contributions to physics are surveyed in How Did Galileo Contribute to Physics?. Galileo died in Arcetri on 8 January 1642, the year Newton was born. The Pope refused to allow a public monument. The story of the trial, was used as a cautionary tale, and the trial itself became, in the eighteenth and nineteenth centuries, a touchstone for the conflict between science and religion. The wider story of the religious reception of the new science is told in the religion and the Church.
The Long Afterlife of the Trial
The trial of Galileo was the most famous single episode in the religious reception of the new science, but it was not the only one. The Catholic Church, came to terms with the heliocentric theory. In 1757, the Pope Benedict XIV ordered the Index to be revised to remove the prohibition on Copernican works; the revision was published in 1758. In 1835, the Dialogue was finally removed from the Index. In 1992, Pope John Paul II acknowledged that the theologians who had condemned Galileo had failed “to recognize the formal distinction between Sacred Scripture and its interpretation.” The acknowledgment was a long time coming, and it is one of the more interesting episodes in the recent history of the Church. is, accurate. The Church did condemn a man for defending a true theory of the cosmos. But the image is also too simple. Galileo was a devout Catholic, and he believed that science and religion, properly understood, did not conflict. The theologians who condemned him were not fools; they were men operating within a framework in which scripture and tradition carried enormous weight, and in which the new claims of the astronomers had not yet been shown to be necessary. The trial of 1633 was a tragedy. It was also a product of its time.
Sources and Further Reading
The standard modern accounts of the trial are Richard Westfall, Galileo and the Churches (Cambridge University Press, 1985), Rivka Feldhay, Galileo and the Church: Political Inquisition or Critical Dialogue? (Cambridge University Press, 1995), and the more recent Pietro Redondi, Galileo: Heretic (Princeton University Press, 1987; originally Italian 1983), which reopened the question of the 1616 injunction. The long afterlife is treated in the standard histories of the Galileo case by Annibale Fantoli, The Disputed Injunction and Its Place in Galileo’s Trial (1984), and Maurice Finocchiaro, The Galileo Affair (University of California Press, 1989). The documents of the trial are collected in Finocchiaro’s The Galileo Reader (Oxford, 1987).