c. 1219/20–c. 1292 · English Franciscan friar, philosopher and polymath
Roger Bacon studied at Oxford, lectured on Aristotle at Paris, joined the Franciscans, and then spent years arguing, mostly to people who had not asked, that Christian learning was in a bad way and that mathematics and languages were the way out of it. The Opus Majus was his case for the prosecution, written at speed for Pope Clement IV in 1267. Its fourth part is a sustained argument that mathematics underpins every other science — which is why the sentence people hand to Galileo is his, and why he would have been pleased to hear it repeated and irritated to lose the credit.