§ 103.2. On account of their characteristic tendencies Avicenna was most popular with the Schoolmen and after him Algazel, while Averroes, though carefully studied and secretly followed by some, was generally regarded with suspicion and aversion. Among his secret admirers was Simon of Tournay, about A.D. 1200, who boasted of being able with equal ease to prove the falseness and the truth of the church doctrines, and declared that Moses, Christ, and Mohammed were the three greatest deceivers the world had ever seen. The Parisian scholars ascribed to Averroes the =Theory of a twofold Truth=. A positive religion was required to meet the religious needs of the multitude, but the philosopher might reach and maintain the truth independently of any revealed religion. In the Christian West he put this doctrine in a less offensive form by saying that one and the same affirmation might be theologically true and philosophically false, and _vice versa_. Behind this, philosophical scepticism as well as theological unbelief sought shelter. Its chief opponents were Thomas Aquinas and Raimund Lull, while at a later time Duns Scotus and the Scotists were inclined more or less to favour it. § 103.3. =The Appearance of the Mendicant Orders.=--The Dominican and Franciscan orders competed with one another in a show of zeal for the maintenance of the orthodox doctrine, and each endeavoured to secure the theological chairs in the University of Paris, the principal seat of learning in those days. They were vigorously opposed by the university corporation, and especially by the Parisian doctor William of St. Amour, who characterized them in his tract _De periculis novissimorum temporum_ of A.D. 1255 as the precursors of antichrist. But he was answered by learned members of the orders, Albert the Great, Aquinas, and Bonaventura, and finally, in A.D. 1257, all opposition on the part of the university was checked by papal authority and royal command. The Augustinians, too, won a seat in the University of Paris in A.D. 1261.--The learned monks gave themselves with enthusiasm to the new science and applied all their scientific gains to polemical and apologetical purposes. They diligently conserved all that the earlier Fathers down to Gregory the Great had written in exposition of the doctrine and all that the later Fathers down to Hugo St. Victor and Peter the Lombard had written in its defence. But what had been simply expressed before was now arranged under elaborate scientific categories. The Summists of the previous century supplied abundant material for the work. Their _Summæ sententiarum_, especially that of the Lombard, became the theme of innumerable commentaries, but besides these, comprehensive original works were written. These were no longer to be described as _Summæ sententiarum_, but assumed with right the title of _Summæ theologiæ_ or _theologicæ_.