The trial of Galileo Galilei ended on June 22, 1633, when the Roman Inquisition in Rome found the astronomer guilty of “vehement suspicion of heresy” for defending the idea that the Earth moves around the Sun. He was made to kneel and publicly renounce his views, his Dialogue Concerning the Two Chief World Systems was banned, and he spent the last nine years of his life under house arrest. The case turned less on whether he was scientifically right than on whether he had defied a direct Church order issued seventeen years earlier.
How Galileo Ended Up on Trial
The legal roots of the trial ran back to 1616. That year, a panel of theological consultants declared that a stationary Sun at the center of the universe was “foolish and absurd in philosophy, and formally heretical” because it contradicted scripture.1Inters.org. Galileo, for Copernicanism and for the Church, a Historical Report On March 5, the Congregation of the Index issued a formal decree prohibiting Copernicus’s On the Revolutions of the Heavenly Spheres and “all other books which teach the same.”2Inters.org. 1616 Decree of the Holy Congregation for the Index against Copernicanism
Galileo was not named in the decree, but he was warned personally. Cardinal Robert Bellarmine told him the Copernican doctrine could not be “defended or held,” and later gave him a signed certificate confirming that Galileo had only been “notified of the declaration made by the Holy Father” and had not been forced to recant anything.3Douglas Allchin. Galileo Trial – 1616 Documents That certificate would become his main defense weapon in 1633.
A second, much stricter document also sat in the Vatican files. A minute recorded by the Commissary General of the Holy Office stated that Galileo had been ordered not to hold, teach, or discuss Copernicanism “in any way whatsoever.” It was unsigned, carried no witness signatures, and did not follow standard Inquisition procedures. Scholars have long questioned whether it was authentic or inserted later.4Famous Trials. Admonition (Injunction?) of Galileo Authentic or not, when it resurfaced in 1632 it gave prosecutors the leverage they needed.
For sixteen years Galileo largely avoided the subject in print. Then in 1632 he published the Dialogue, a conversation among three characters: Salviati, a sharp Copernican; Sagredo, an open-minded listener; and Simplicio, a committed Aristotelian defending the geocentric view. The form gave Galileo cover to air the Copernican case while attributing it to a fictional speaker. The cover did not hold. Salviati’s arguments were consistently stronger, and Galileo had placed an argument on divine omnipotence that Pope Urban VIII himself had suggested into the mouth of Simplicio. Urban, who had been Galileo’s friend and admirer, became convinced that Galileo had exploited their friendship and mocked him in print.5University of Navarra. New Light on the Galileo Affair The Pope ordered an investigation.
The Charge Against Him
The Inquisition charged Galileo under the category of “vehement suspicion of heresy,” a serious intermediate level of guilt in Church law.6Constellations. The Complexity of the Galileo Affair This was not a declaration that he was a heretic outright. It meant the court held that his conduct and writings strongly indicated he privately believed forbidden doctrines, even if he had not openly declared himself a heretic. The distinction mattered. A declared heretic faced far harsher penalties, potentially death; someone “vehemently suspected” could escape the worst consequences through a formal recantation.
The charge rested on two pillars. Galileo had allegedly violated the 1616 order not to teach or defend Copernicanism, with the disputed injunction supplying the textual basis. And the Dialogue itself was offered as evidence that he had promoted the Copernican model as physically true rather than treating it as a mathematical exercise. The framing let the court pursue the case as disobedience to Church authority rather than as a scientific dispute.
How the Trial Ran
Galileo arrived in Rome in February 1633 and was allowed to stay at the Tuscan embassy rather than in an Inquisition cell, a concession to his age, his health, and his Medici connections.7Famous Trials. The Trial of Galileo: A Chronology The proceedings played out across four formal depositions over roughly ten weeks.
At the first deposition on April 12, he was questioned about the 1616 warning and the Dialogue. He acknowledged that Bellarmine had told him the Copernican opinion could not be held or defended, but claimed not to remember the more restrictive language of the disputed injunction, the additional prohibition against teaching the doctrine “in any way whatsoever.”8Cambridge Core. Galileo’s Non-Trial (1616), Pre-Trial (1632-1633), and Trial (May 10, 1633)
At the second deposition on April 30, he shifted ground and offered a partial admission. He conceded that a reader unfamiliar with his intentions might understand the Dialogue‘s arguments as supporting “the false side,” and insisted that favoring Copernicanism had been “foreign to his intention.” Even a sympathetic reader of the book would have found that hard to swallow.
The third deposition on May 10 was the formal trial. Given a chance to mount a full defense, Galileo declined any sweeping account. He admitted partial guilt while defending his good intentions, and produced the Bellarmine certificate as his central piece of evidence. His argument was clever. Because Bellarmine’s certificate described only the general prohibition applied to everyone under the Index decree, he claimed he had no reason to believe he was under any special personal restriction that would have required disclosure to the censor who approved the Dialogue. He conceded the disputed injunction apparently contained additional words forbidding him to “teach it in any way,” but said he had not remembered those terms. He ended by placing himself at the court’s mercy.
The fourth deposition, on June 21, was the most coercive phase. The Pope had ordered that Galileo be interrogated about his actual private beliefs, under threat of torture. This procedure, known as the examen rigorosum, was a standard step in Inquisition cases where a guilty plea left doubt about the defendant’s sincerity. In Galileo’s case the examination went only as far as the threat; torture was not applied.9The Galileo Project. Procedure of the Roman Inquisition Pressed on whether he held, or had ever held, that the Sun was the center of the world, he did not change his answers. He maintained that after the 1616 determination he had accepted the traditional view as true.
The Verdict and the Penalties
Sentence was issued the following day, June 22, 1633. Ten cardinals were named as judges, but only seven signed. The three who did not sign were Francesco Barberini (the Pope’s nephew), Caspar Borgia, and Laudivio Zacchia; no public explanation was given.10Famous Trials. Papal Condemnation (Sentence) of Galileo
Galileo was made to kneel at the Convent of Minerva in Rome and read aloud a prepared abjuration. He formally renounced and cursed his past errors on the movement of the Earth and swore he would never again say or write anything that could bring similar suspicion upon him.11Famous Trials. Recantation of Galileo The abjuration was a mandatory requirement for anyone found guilty under vehement suspicion of heresy. Without it, he would have been treated as an unrepentant heretic and faced far worse consequences.
The court imposed several penalties. Galileo was condemned to “formal prison of this Holy Office” at the court’s pleasure. The Dialogue was “prohibited by public edict.” As a spiritual penance, he was ordered to recite the seven penitential psalms once a week for three years.12Gordon State College. The Sentence and Abjuration of Galileo The sentence reserved the court’s right to “moderate, commute, or take off” these penalties, and the court exercised that discretion almost immediately.
What Happened to Galileo After the Verdict
The prison sentence was commuted within days. Cardinal Francesco Barberini arranged for Galileo to be transferred to the custody of the Archbishop of Siena rather than confined in a monastery for prolonged penitence, as had originally been planned.13Famous Trials. The Trial of Galileo: Key Figures He also spent a brief period at the Villa Medici in Rome after his abjuration.14Villa Medici. Sleeping at Villa Medici Eventually he was allowed to return to his own villa in Arcetri, outside Florence, where he lived under house arrest for the rest of his life. His daughter, Sister Maria Celeste, a cloistered nun, took on the weekly recitation of the penitential psalms on his behalf.15Linda Hall Library. Suor Maria Celeste
Confinement did not end his work. He completed Two New Sciences, a foundational text on mechanics and the strength of materials, which was smuggled out of Italy and published in the Dutch Republic in 1638. By then he had gone completely blind. He died at Arcetri in January 1642 at the age of seventy-seven.
The Church’s Later Reversal
The Church walked back its position on Copernicanism slowly and quietly. In 1820, under Pope Pius VII, the remaining prohibitions on books teaching the Earth’s motion were formally removed, prompted by a Roman professor who wanted permission to publish a heliocentric astronomy textbook. The Pope ruled that “no obstacles exist for those who sustain Copernicus’s affirmation regarding the earth’s movement in the manner in which it is affirmed today, even by Catholic authors.”16Vatican Observatory. Decree of Approval for the Work Elements of Astronomy by Giuseppe Settele
The case of Galileo himself took longer. In 1981, Pope John Paul II established a commission to reexamine the affair. After eleven years, the commission delivered its findings on October 31, 1992, in a formal address to the Pontifical Academy of Sciences. The Pope described the affair as a “tragic mutual incomprehension.” The commission acknowledged that the theologians of Galileo’s era had failed to reinterpret scripture in light of new scientific evidence, while also arguing that Galileo had not provided sufficient proof for Copernicanism at the time.17Vatican Observatory. The Church’s Most Recent Attempt to Dispel the Galileo Myth The commission stopped short of issuing a formal apology or declaring the 1633 verdict legally void.