In December 1613, a key event took place, setting events in motion that ultimately led to Galileo's trial. Benedetto Castelli, a Benedictine monk, professor of physics at Pisa, and a disciple of Galileo, had breakfast with the Grand Duke and Duchess of Tuscany, who were Galileo's patrons. They asked Castelli to explain the recent astronomical discoveries. This led naturally to a discussion of the heliocentric theory. Cosimo Boscaglia, a professor of philosophy also at Pisa, was ``whispering in the ear of Her Ladyship'' and began to argue against the earth's motion, saying it was against Scripture.
Here are some scriptural passages frequently cited as opposed to the heliocentric theory (King James translation):
The Grand Duchess, a pious and devout lady, was concerned about these objections, and Castelli answered as best he could. Later, he wrote to Galileo telling him of the incident. Galileo replied, laying out some of his own ideas on scriptural interpretation. In essence, he argued that since God is the author of both Scripture and Nature, there cannot be any contradiction between the things we learn from each. There is only one truth, and if a truth of science appears to contradict something in Scripture, then it means that we do not fully understand one or the other. One should not use Scripture as the basis for study of the physical realm, since it was, in the words of Cardinal Baronius, ``intended to teach us how to go to heaven, not how the heavens go.'' This letter to Castelli was fairly widely circulated although not published.
Galileo, hearing that various rumors and errors about him were being spread, decided to expand this letter and publish it. This resulted in his famous Letter to the Grand Duchess Christina. Although he wrote this essay in order to defend himself against allegations of heresy, the effect of publishing it was to irritate the Church authorities, who up to this point had not been inclined to get involved in the matter. In their view, Galileo was a mere mathematician, unqualified to speak about matters of theology, and it was presumptuous of him to do so. Cardinal Robert Bellarmine, at that time the Church's chief theologian, sent signals through the Tuscan ambassador to the Vatican and other friends of Galileo, that Galileo would be safe from the Inquisition provided that he treated the Copernican theory only as a hypothesis and not as physically true, and that he did not try to reconcile the theory with Scripture. Galileo was unwilling to accept this advice, being convinced (although without the solid proofs that would come only long after he was dead) of the physical reality of the Copernican model, and also unwilling to be quiet.
In February 1615 Nicolò Lorini, a Dominican preacher and professor of history at Florence, filed a complaint against Galileo with the Roman Inquisition, giving them an insidiously altered copy of Galileo's letter to Castelli. For instance, Galileo wrote ``There are in Scripture words which, taken in the strict literal meaning, look as if they differed from the truth.'' Lorini altered this to read ``which are false in the literal meaning.'' Galileo wrote ``Scripture has not abstained from somewhat concealing its most essential dogmas; thus attributing to God himself properties contrary to and very far from his essence.'' Lorini changed ``concealing'' to ``perverting.'' The Inquisitors were suspicious of Lorini's motives, and quietly asked Castelli for a correct copy of the letter, but it seems that for various reasons they never received one. In the end, no conclusive evidence was found against Galileo at this time.