In 1215, the Apostolic legate, Robert de Courçon, issued new rules governing who could become a professor. To teach the arts, a candidate had to be at least twenty-one, to have studied these arts at least six years, and to take an engagement as professor for at least two years. For a chair in theology, the candidate had to be thirty years of age, with eight years of theological studies, of which the last three years were devoted to special courses of lectures in preparation for the mastership. These studies had to be made in the local schools under the direction of a master. In Paris, one was regarded as a scholar only by studies with particular masters. Lastly, purity of morals was as important as reading. The licence was granted, according to custom, gratuitously, without oath or condition. Masters and students were permitted to unite, even by oath, in defence of their rights, when they could not otherwise obtain justice in serious matters. No mention is made either of law or of medicine, probably because these sciences were less prominent.