Richard Kilvington, Master of Arts (c. 1325) and Doctor of Theology (c. 1335) at Oxford, was a member of Richard de Bury's household, later becoming archdeacon and finally dean of Saint Paul's Cathedral in London. Along with Thomas Bradwardine, Kilvington formed the first academic generation of the school known as the "Oxford Calculators." All of Kilvington's philosophical works—Sophismata and Quaestiones super De generationeet corruptione (written before 1325), Quaestiones super Physicam (c. 1326) and Quaestiones super libros Ethicorum (before 1332)—and his theological questions on Lombard's Sentences (c. 1334) stem from lectures at Oxford. In his Physics, Kilvington found an original way to apply the Euclidean theory of ratios to a new formula relating speeds, forces, and resistances in motions. Because the new rule avoided a serious weakness in Aristotle's theory of motion, nearly everyone adopted it, including the most famous Oxford Calculator, Thomas Bradwardine, in his renowned...