He prepared a remarkable little text-book, called _Yea and Nay_, containing seemingly contradictory opinions of the church fathers upon particular questions. The student was left to reconcile the contradictions, if he could, by careful reasoning; for Abelard held that a constant questioning was the only path to real knowledge. His free way of dealing with the authorities upon which men based their religious beliefs seemed wicked to many of his contemporaries, especially to St. Bernard, who made him a great deal of trouble. Nevertheless it soon became the fashion to discuss the various doctrines of Christianity with great freedom and to try to make a well-reasoned system of theology by following the rules of Aristotle's logic. It was just after Abelard's death (1142) that Peter Lombard published his _Sentences_, already described. Abelard did not found the University of Paris, as has sometimes been supposed, but he did a great deal to make the discussions of theological problems popular, and by his attractive method of teaching he greatly increased the number of those who wished to learn. The sad story of his life, which he wrote when he was worn out with the calamities that had overtaken him, is the best and almost the only account which exists of the remarkable interest in learning which explains the origin of the University of Paris.[173] [Sidenote: Origin of the University of Paris.] Before the end of the twelfth century the teachers had become so numerous in Paris that they formed a union, or guild, for the advancement of their interests. This union of professors was called by the usual name for corporations in the Middle Ages, _universitas_; hence our word "university." The king and pope both favored the university and granted the teachers and students many of the privileges of the clergy, a class to which they were regarded as belonging, because learning had for so many centuries been confined to the clergy. [Sidenote: Study of the Roman and canon law in Bologna.] [Sidenote: The _Decretum_ of Gratian.]