BACON, ROGER (c. 1214–c. 1292), philosopher and Franciscan friar. Born in the west of England of a wealthy family, for most of his life Bacon alternated between England and France. His first, if not his only, university education was at Oxford, and soon thereafter he pioneered in lecturing on Aristotle's metaphysics and on natural philosophy at Paris. Several Artistotelian commentaries survive from this period, but Bacon was soon to undergo a profound intellectual reorientation, inspired at least partly by another work that he believed to be by Aristotle, the Secretum secretorum, a long letter of advice on kingship supposedly written to Alexander the Great.

Bacon's intellectual universe was peopled with heroes and villains. Aristotle was a particularly great ancient hero, while among the few contemporaries admitted to the pantheon were Robert Grosseteste and Adam Marsh. Grosseteste (whom Bacon may not have known personally) had been a lecturer...