physics and metaphysics of Aristotle, and sought to demonstrate that these theories were in perfect harmony with the doctrines of Judaism. "It is an error generally current," says Ibn Daud in the preface of his book, "that the study of speculative philosophy is dangerous to religion. True philosophy not only does not harm religion, it confirms and strengthens it." Maimonides with Aristotle against the MoteKallamin The authority of Ibn Daud, however, did not suffice to give permanence to Aristotelianism in Judaism. This accomplishment was reserved for Maimonides, who discussed the relevance of the philosophy of Aristotle to Judaism; and to this end he composed his immortal work, "Dalalat al-Ḥairin" (Guide for the Perplexed) —known better under its Hebrew title "Moreh Nevuchim"—which served for many centuries as the subject of discussion and comment by Jewish thinkers. In this work, Maimonides, after refuting the propositions of the Motekallamin, considers Creation, the Unity of God, the Attributes of God, the Soul, etc., and treats them in accordance with the theories of Aristotle to the extent in which these latter do not conflict with religion. For example, while accepting the teachings of Aristotle upon matter and form, he pronounces against the eternity of matter. Maimonides against Aristotle In addition to pronouncing against the eternity of matter, neither does he accept Aristotle's theory that God can have a knowledge of universals only, and not of particulars. If He had no knowledge of particulars, He would be subject to constant change. Maimonides argues: "God perceives future events before they happen, and this perception never fails Him. Therefore there are no new ideas to present themselves to Him. He knows that such and such an individual does not yet exist, but that he will be born at such a time, exist for such a period, and then return into non-existence. When then this individual comes into being, God does not learn any new fact; nothing has happened that He knew not of, for He knew this individual, such as he is now, before his birth" ("Moreh," i. 20). While seeking thus to avoid the troublesome consequences certain Aristotelian theories would entail upon religion, Maimonides could not altogether escape those involved in Aristotle's idea of the unity of souls; and herein he laid himself open to the attacks of the orthodox. Averroism Ibn Roshd (or Ibn Rushd or Averroes), the contemporary of Maimonides, closes the philosophical era of