 To Albalag, Avicenna’s proof of God as Necessary Existent appeared to involve flagrant deviations from Aristotle. Firstly, Avicenna’s procedure for establishing the existence of the First Principle in the science of metaphysics is methodologically incorrect. (Tiqqun n.8: 13–14). Appealing to Averroes, Albalag argues that the existence of the prime mover must be accepted from natural philosophy—not insofar as it is the deity—while metaphysicians proceed therefrom in examining its states and attributes. Obviously, the theoretical basis for this argument is Aristotle’s rule that “no master of any art can demonstrate the proper principles of his art” (Metaphysics IV 1003a21–22), which, according to Averroes, means that a given science does not demonstrate the existence of its subject, but must concede to their existence either as something which is “self-evident” or as “something that has been demonstrated in another science” (Wolfson 1950–1 : 691). Since the First Principle is the subject matter of metaphysics, its existence cannot be established in that specific science.