The Kalamistic proofs for the unity of God are similarly identical for the most part with those found in Saadia, Bahya and others, and we need only mention Maimonides's criticism that they are inadequate unless we assume with the Mutakallimun that all atoms in the universe are of the same kind. If, however, we adopt Aristotle's theory, which is more plausible, that the matter of the heavenly bodies is different from that of the sublunar world, we may defend dualism by supposing that one God controls the heavens and the other the earth. The inability of the one to govern the domain of the other would not necessarily argue imperfection, any more than we who believe in the unity of God regard it as a defect in God that he cannot make a thing both be and not be. This belongs to the category of the impossible; and we should likewise class in the same category the control of a sphere that is independent of one and belongs to another. This is purely an _argumentum ad hominem_, for Maimonides does not regard the sublunar and superlunar worlds as independent of each other. He recognizes the unity of the universe.[267] Maimonides closes his discussion of the Kalamistic system by citing their arguments for incorporeality, which he likewise finds inadequate, both because they are based upon God's unity, which they did not succeed in proving (Saadia, in so far as he relates the two, bases unity upon incorporeality), and because of inherent weakness.[268] Having disposed of the arguments of the Mutakallimun, Maimonides proceeds to prove the existence, unity and incorporeality of God by the methods of the philosophers, _i. e._, those who, like Alfarabi and Avicenna, take their arguments from Aristotle. The chief proof[269] is based upon the Aristotelian principles of motion and is found in the eighth book of Aristotle's Physics. We have already met this proof in Ibn Daud (_cf._ above, p. 217), and the method in Maimonides differs only in form and completeness, but not in essence. There is, however, this very important difference that Ibn Daud fights shy of Aristotle's theory of the eternity of motion and time, thus losing his strongest argument for God's infinite power and incorporeality (_cf._ p. 218); whereas Maimonides frankly bases his entire argument from motion (provisionally to be sure) upon the Aristotelian theory, including eternity of motion. With this important deviation there is not much in this part of the Maimonidean discussion which is not already contained, though less completely, in the "Emunah Ramah" of Abraham Ibn Daud. We should be tempted to omit these technical arguments entirely if it were not for the fact that it is in the form which Maimonides gave them that they became classic in Jewish philosophy, and not in that of Ibn Daud.