The middle and the latter half of the thirteenth century were years of violent controversy in the University of Paris. Fundamentally the source of this was the jealousy of the secular clergy against the Mendicant orders, which had succeeded in establishing themselves in the University earlier in the century, the Dominicans securing their first chair in 1217, the Franciscans theirs in 1219. Apprehensive lest the Friars should achieve a complete predominance, the seculars under the leadership of Gerard of Abbeville and the acrimonious William of Saint-Amour led a heated attack upon them, first only on the practical question of university privileges. But it was not long before matters of doctrine were involved, and regulars and seculars were soon denouncing each other as heretics and antichrist.[86] It is not easy to discover what was the doctrinal position of the seculars, but they seem to have reproached the Dominicans at all events with overfondness for philosophy as distinct from theology.[87] Together with the contest between seculars and regulars in the University there went also one between the two great Mendicant orders. The same charge seems to have been preferred against the Prædicants by their rivals. They cared too much for knowledge that was not wholly sacred; they were too scientific, too intellectualist.[88] Such is the gist of the diatribes launched against the Dominicans, especially Thomas Aquinas, by Archbishop Peckham.[89] There is no doubt that he deliberately tried to involve Aquinas in the suspicion of Averrhoïsm. A certain Gilles de Lessines, sending to Albertus Magnus a list of fifteen errors current in Paris, includes in the number thirteen definitely Averrhoïst doctrines together with two theories of Aquinas, not Averrhoïst, to which, however, the Augustinians took exception.[90] Clearly the Franciscans were endeavouring to discredit not only the Averrhoïsts, but the Aristotelians. In the year 1270 there appeared two important treatises: the one by a certain Siger of Brabant, entitled ‘De anima intellectiva,’ the other by Aquinas, ‘De unitate intellectus contra Averroïstas.’ The latter is defending himself vigorously against the charge of Averrhoïsm by himself vigorously attacking the Averrhoïsts. In a sermon preached before the University of Paris St. Thomas vehemently denounced the self-confidence and self-sufficiency of the Averrhoïsts, and contrasted the contradictions and the uncertainties of philosophy with the clearness and certitude of revealed religion.[91] In this same year 1270 the Bishop of Paris, Etienne Tempier, solemnly condemned the thirteen propositions mentioned in Gilles de Lessines’ letter to Albertus of Cologne. They were the doctrines being taught at the time by the two leaders of Averrhoïsm in the University, the Siger of Brabant just mentioned and Boëthius of Dacia.