Giles of Rome, the scholastic philosopher whose real name was Aegidius Colonna Romanus, was born in Rome. Giles entered the Augustinian order of hermits in 1265 and subsequently studied at the University of Paris, where from 1268 to 1272 he was probably the pupil of Thomas Aquinas, who was then lecturing at the university as Dominican regent master. In 1277 the bishop of Paris made his far-reaching condemnation of 219 theses, mainly of Aristotelian origin but also including a number of Thomist propositions. Among these were Thomas's doctrine that each being contains only one substantial form, as opposed to the traditional Augustinian belief in a plurality of forms. Giles, a young scholar, joined in the ensuing controversy with the publication of a sharply worded defense of the Thomist view, the Liber Contra Gradus et Pluralitatem Formarum. He attacked the Augustinian doctrine as being contrary to...