THIRD TRIP • 10 DECEMBER 1615–4 JUNE 1616
Four years after his second trip, Galileo decided that it was time to return to Rome. In the meanwhile, he had published a Discourse on Floating Bodies, and Letters on the Sunspots, in which he argued that sunspots were some kind of clouds near the surface of the Sun. This was a blow to Aristotelianism and an argument in favor of a new cosmology. But Galileo did not want to travel to Rome merely to discuss astronomy. He had come to realize that what he had to do was defend himself against the accusation that what he taught went against Scripture.
Galileo had become aware of the sensitivities of the ecclesiastical authorities when he had submitted his Letters on the Sunspots to obtain the license to print it. The cavils of the censors forced successive revisions, and brought Galileo into contact with the day-to-day running of the Counter Reformation. The book was to have opened with a letter from Mark Welser in which he quoted from Matthew 11:12, “The kingdom of heavens suffers violence, and men of violence take it by force.” The censors objected to the quotation because it might give the