annual motion was a slow movement towards the East, so if God had commanded it to stop, the daily movement towards the West would no longer have been counteracted and as a result the day would actually have got slightly shorter rather than longer. However if we assume the universe to be as Copernicus described it, the Sun is at the centre and its rotation drives the rotation of all the planets. Thus if God had ordered the Sun to stop turning, everything would have stopped and the day would have been longer, just as the Bible described. Analysis Two aspects of Galileo's letter are particularly worthy of note. First, his boldness in venturing into the field of exegesis, where he was bound to upset many theologians who would not welcome his contributions. Second, his rhetorically brilliant argument was based on a fundamental contradiction; he began by arguing that faith and science were distinct, and that the Bible could not be used as the basis for arguments about science; he then went on to show, according to some novel and clever arguments, that actually the Bible supported his own scientific views. His letter argues a position on scriptural authority which is very similar in substance, if not in tone, to that set out by the Catholic Church itself centuries later, in Leo XIII's 1893 encyclical, Providentissimus Deus. Emphasising that the Bible makes use of figurative language and is not meant to teach science, this argues: "...here is the rule also laid down by St. Augustine, for the theologian: "Whatever they [i.e. scientists] can really demonstrate to be true of physical nature, we [i.e. theologians] must show to be capable of reconciliation with our Scriptures; and whatever they assert in their treatises which is contrary to these Scriptures of ours, that is to Catholic faith, we must either prove it as well as we can to be entirely false, or at all events we must, without the smallest hesitation, believe it to be so." Likewise, Galileo accepted that the Bible was infallible in matters of doctrine, but he agreed with Cardinal Baronius's observation that it was "intended to teach us how to go to heaven, not how the heavens go." He also pointed out that both St. Augustine and St. Thomas Aquinas had taught that scripture had not been written to teach a system of astronomy, citing St. Augustine's comment that