We see here a number of ideas foreign to Aristotle, which are found first in Philo the Jew and appear later in mediæval philosophy. Thus God as a Being absolutely unknowable, of whom negations alone are true just because he is the acme of perfection and bears no analogy to the imperfect things of our world; matter in our world as the origin of evil, and the existence of matter in the intelligible world--all these ideas will meet us again in Ibn Gabirol, in Ibn Daud, in Maimonides, some in one, some in the other. Alike in respect to Aristotle as in reference to Plotinus, the Jewish philosophers found their models in Islamic writers. The "Theology of Aristotle" which, as we have seen, is really Plotinian rather than Aristotelian, was translated into Arabic in the ninth century and exerted its influence on the _Brethren of Purity_, a Mohammedan secret order of the tenth century. These men composed an encyclopædia of fifty-one treatises in which is combined Aristotelian logic and physics with Neo-Platonic metaphysics and theology. In turn such Jewish writers as Ibn Gabirol, Bahya, Ibn Zaddik, Judah Halevi, Moses and Abraham Ibn Ezra, were much indebted to the Brethren of Purity. This represents the Neo-Platonic influence in Jewish philosophy. The Arab Aristotelians, Al Kindi, Al Farabi, Avicenna and Averroes, while in the main disciples of the Stagirite, were none the less unable to steer clear of Neo-Platonic coloring of their master's doctrine, and they were the teachers of the Jewish Aristotelians, Abraham Ibn Daud, Moses ben Maimon, Levi ben Gerson. One other phase must be mentioned to complete the parallelism of Islamic and Jewish philosophy, and that is the anti-philosophic attitude adopted by Judah Halevi and Hasdai Crescas. It was not a dogmatic and unreasoned opposition based simply upon the un-Jewish source of the doctrines in question and their incompatibility with Jewish belief and tradition, such as exhibited itself in the controversies that raged around the "Guide" of Maimonides. Here we have rather a fighting of the philosophers with their own weapons. Especially do we find this to be the case in Crescas who opposes Aristotle on philosophic grounds. In Judah Halevi similarly, though with less rigor and little technical discussion, we have nevertheless a man trained in philosophic literature, who found the philosophic attitude unsympathetic and unsatisfying because cold and impersonal, failing to do justice to the warm yearning after God of the religious soul. He could not abide the philosophic exclusion from their natural theology of all that was racial and national and historic in religion, which was to him its very heart and innermost essence. In this attitude, too, we find an Arab prototype in the person of Al Gazali, who similarly attacked the philosophers on their own ground and found his consolation in the asceticism and mysticism of the Sufis.