In December of 1613, Galileo received a letter from Father Castelli, a close friend of his and a fellow astronomer. Castelli had recently dined with the royal family of Tuscany, and he reported how the Grand Duchess Christina had criticized the heliocentric theory for its repudiation of Holy Scripture. Galileo fired back a letter to his friend that would later be published, with the author's permission, across Italy. In it, he declared that scriptural literalism had no place in scientific inquiry. "Inasmuch as the Bible calls for an interpretation differing from the immediate sense of the words," he wrote, "it seems to me that as an authority in mathematical controversy it has very little standing... I believe that natural processes which we perceive by careful observation or deduce by cogent demonstration cannot be refuted by passages from the Bible." Had he halted there, all might have been well, but he went on to offer his own positions on matters of theology: "The primary purpose of the Holy Writ is to worship God and save souls," he argued; his imperious, lecturing tone ruffled feathers and, in its apparent contempt for the teaching authority of the Church, smacked of Protestantism.
The anti-Galilean powers in the Church now had their ammunition. In December 1614, a Dominican priest named Tommasso Caccini viciously condemned the astronomer in a sermon in the Florentine church of Santa Maria Novella. Caccini took as his text a verse in the New Testament's Book of Acts, in which an angel asks Christ's disciples, "Ye men of Galilee, why stand ye gazing up into the heavens?" The verse supplied an excellent pun on Galileo's name–the "men of Galilee" could be understood as the followers of Galileo–although it did not comment on astronomy. In Caccini's hands, however, the words became an assault on the new astronomy, which, he sermonized, ran completely contrary to Christian faith and sacred scripture. The sermon provoked a furor, and although Caccini's superiors in the Dominican order hastily repudiated his words, the damage was done. In mid-March of 1615, Caccini issued a formal complaint against Galileo with the Inquisition, the Church office responsible for rooting out heresy. The Inquisition began to gather evidence against the astronomer in preparation for a trial.
Galileo fought back. He corresponded with Bellarmine, offering the cardinal alternate interpretations of scripture that would accommodate a heliocentric cosmology. He wrote to Grand Duchess Christina of Tuscany, hoping for support from the Medici, and declaring that "nothing physical which sense-experience sets before out eyes, or which necessary demonstrations prove to us, ought to be called into question (much less condemned) upon the testimony of Biblical passages which may have some different meaning beneath their words." Then, in December of 1615, he decided to travel to Rome himself, perhaps remembering his successful tour through the holy city five years before. Once there, he hoped, he could convert the Catholic hierarchy to the Copernican cause. He carried with him new evidence, as well: a "Treatise on the Tides" which linked the ebb and flow of the ocean to the movement of the earth around the sun. (Ironically, this new "evidence," intended to augment the earlier findings, in fact contained no legitimacy: as we now know, the moon's gravity causes the tides, though Galileo's false hypothesis would not be disproved in his lifetime.)
Meanwhile, upon reaching Rome, Galileo found that he had underestimated the obstacles in his path. Bellarmine was an intelligent man, who seems to have genuinely liked Galileo, but his mind was made up: to accept the Copernican theory would require a wholesale rethinking of the Church's view of the natural world, and while he allowed that such a reconsideration might be necessary, it was not something to be rushed into without definite, ironclad proof that Ptolemy and Aristotle were mistaken and Copernicus correct. Therefore, while heliocentricity could be suggested and discussed as a hypothesis, Galileo's insistence that it was definitely and positively true constituted a breaching of proper boundaries. Of course, the level of "proof" that Bellarmine demanded could never be achieved–in his view, no empirical findings could override the Bible's authority–and the effect of Bellarmine's position was thus to paralyze scientific inquiry.
Worse still, the Church soon took up a position exceeding Bellarmine's cautious hostility. In March 1615 a commission appointed by Pope Paul V delivered its opinion on the heliocentricity-geocentricity debate, declaring solemnly (and irrationally) that "the view that the sun stands motionless at the center of the universe is foolish, philosophically false, and utterly heretical... the view that the earth is not the center of the universe and even has a daily rotation is philosophically false, and at least an erroneous belief." The Pope, no intellectual heavyweight himself, gave his blessing to the pronouncement. (Ironically, of course, the sun does not stand motionless at the center of the universe–it rotates at the center of the solar system–so the commission was partially, albeit unintentionally, correct.) Bellarmine was delegated the duty of requesting Galileo's submission to this edict, and it was for this that the aging cardinal, one of the great minds of his age, would be forever remembered. His mind–conditioned by the long struggle to defend the Church from Protestantism at all costs–could not make the leap of vision necessary to recognize the terrible error being made by his beloved Church.
With the threat of the Inquisition looming over his head, Galileo agreed to submit to the edict. He lingered in Rome for a few months, and then departed in June 1615, forlornly writing to a friend that "of all the hatreds, none is greater than that of ignorance against knowledge."