While the Dialogue Concerning the Two Chief World Systems initially enjoyed a favorable response, Galileo's enemies soon went on the attack, and he had given them plenty of ammunition in his new work. The Dialogue harshly criticized the Jesuits, now his dedicated foes; the work referred to one Jesuit, Father Christopher Scheiner, as "vain and foolish." These unnecessary barbs were typical of the undiplomatic and combative Galileo, and they proved his undoing. The Jesuits closed ranks against him, and as the Inquisition began to look more closely at the work, they went to Urban VIII and pointed out a particularly unfortunate passage in the Dialogue, in which Simplicio, the anti-Copernican foil, repeats almost verbatim arguments that the Pope himself had made to Galileo nearly a decade before. Seeing his own arguments repeated by the "simple" character in the dialogue, Urban felt betrayed, and his long-held sympathy for Galileo evaporated. "He did not fear to make sport of me," the Pope declared. The Inquisition now took charge, forbidding further sale of the work in August 1632, and on September 23, Galileo was summoned to Rome. His friends protested that his advanced age made such a trip unadvisable, but their arguments fell on deaf ears; the Church insisted on his appearance in trial, and in February, 1633 Galileo made his way to the holy city.
The astronomer was an old man now, nearing seventy, and weakened by ailments real and imaginary. For two months, the Inquisition delayed, and Galileo stayed in the home of the Tuscan ambassador, his mood fluctuating between hope and despair. Then, on April 12, authorities summoned him to the Palace of the Inquisition, in the Vatican, and interrogated him for the first time. He was accused of having violated Cardinal Bellarmine's 1616 injunction against regarding teaching Copernicus's system as "fact"; in response, he protested that he had taught it as hypothesis only, and not as truth, and defended the publication of his Dialogue by insisting that he had received all the necessary permissions by the Church. His interrogators made little headway, and after the end of this first session, they kept him as a prisoner in the Vatican until April 30, where he lived in well appointed but confining quarters. He hoped for the intervention of Urban VIII, whom he still counted as a friend, but the Pope was deliberately distancing himself from the proceedings. Meanwhile, Galileo had fallen ill, and his inquisitors took advantage of his condition, by hinting at the tortures that might await him if he did not confess his errors.
Letters from his daughter Virginia–now the deeply pious Sister Maria Celeste–urged him to submit to God's will, and the first cracks appeared in Galileo's armor. On April 30, he confessed to having been too prideful in this Dialogue, and having stated the Copernican case too strongly; he offered to write a hundred additional pages to correct this difficulty. This suggestion was a fantasy, but authorities permitted him to return to the Tuscan embassy. On May 10, the Inquisition examined him again, and now he begged for mercy, asking his judges to consider his advanced age and take pity on him. Everyone now wanted a speedy resolution to the matter, but somehow it dragged on into June, when the Inquisition finally broke its famous prisoner: they declared him guilty of heresy and promised mercy only on the condition that he renounce his errors; Galileo, his will to resist gone, declared himself to be firmly convinced of the truth of Ptolemy's system. Publicly kneeling before his tribunal, he declared, "with a sincere heart and unfeigned faith I abjure, curse, and detest the said errors and heresies, and generally every other error and heresy contrary to the... Holy Church, and I swear that I will nevermore in future say or assert anything... which may give rise to a similar suspicion of me." Later legend would assert that he added, under his breath, "Eppur si muove!" (And yet it does move!), but this is mere dramatic additive. The Inquisition had won. Galileo was sentenced to "the prison of this Holy Office for a period determinable at our pleasure;" he was first confined in Rome, then transferred to a friend's house in Siena, and then allowed to live under house arrest in his own villa outside Florence. He would remain there until his death eight years later.
The trial of Galileo brought to fruition what had begun with the mistaken decision of Paul VI's 1616 commission that the Church turn its back on the Copernican system. The event constituted a personal disaster for Galileo, and his rash behavior and talent for making enemies and alienating friends must bear some of the blame for the tragedy. But the real guilt lay with the Church, and the cardinals and inquisitors who could not muster vision when vision was required; they had dealt Catholicism, and all of European culture, a terrible blow: Counter-Reformation zeal had triumphed over Renaissance creativity, and in the great Catholic countries–Italy, Spain and France–a pall fell over scientific endeavor and philosophical speculation. Nothing, not even prohibition by the Inquisition, could halt the spread of the Dialogue and the triumph of the Copernican system, but after Galileo, science and philosophy would lose its Renaissance vibrancy. Meanwhile, a terrible example had been set, a martyr had been made, and a great, unnecessary divide had been opened between religion and science, when they might have walked together in their search for truth about the universe, at least for the next few centuries.