Bahya Ibn Pakuda. Joseph Ibn Zaddik is the first who finds it necessary to give an independent treatment of the sciences before proceeding to construct his rehgious philosophy, and in so doing he expounds the concepts of matter and form, substance and accident, genesis and destruction, the four elements and their natures and so on—all these Aristotelian concepts. Ibn Daud follows in the path of Ibn Zaddik and discusses the relevant concepts of potentiality and actuality and the nature of motion and infinity, upon which his proof is based of the existence of God. Maimonides clears the ground first by a thorough criticism and refutation of the Kalamistic physics, but he does not think it necessary to expound the Aristotelian views which he adopts. He refers the reader to the original sources in the Physics and Metaphysics of Aristotle, and contents himself with giving a list of principles which he regards as established. Aristotle is now the master of all those who know. And he reigns supreme for over a century until the appearance of the "Or Adonai" of Hasdai Crescas, who ventured to deny some of the propositions upon which Maimonides based his proof of the existence of God—such, for example, as the impossibility of an infinite magnitude, the non-existence of an infinite fulness or vacuum outside of the limits of our world, the finiteness of our world and its unity, and so on.
These discussions of the fundamental principles of physics were applied ultimately to prove the existence of God. But there was a difference in the manner of the application. During the earlier period before the "Emunah Ramah" of Abraham Ibn Daud was written, the method employed was that of the Arabian Mutakallimun. That is, the principles of physics were used to prove the creation of the world in time, and from creation inference was made to the existence of a Creator, since nothing can create itself. The creation itself in time as opposed to eternity was proved from the fact of the composite character of the world. Composition, it was said, implies the prior existence of the constituent elements, and the elements cannot be eternal, for an infinite past time is unthinkable. This method is common to Saadia, Bahya, Joseph Ibn Zaddik, and others.
With the appearance of Ibn Daud's masterpiece, which exhibits a more direct familiarity with the fundamental ideas of Aristotle, the method changed. The existence of God is proved directly from
