 It was well known among the scholastics that Avicenna and Averroes disagreed about the subject matter of metaphysics. In the two opening chapters of his Metaphysics, Avicenna argues that no science can demonstrate the existence of its proper subject, and that hence God, whose existence is proven in metaphysics, cannot be its proper subject. The subject (mawḍūʿ, subiectum) of metaphysics is being as being. What is sought after (maṭlūb, quaesitum) in metaphysics, is that which unconditionally accompanies being: such as the causes of being, among which God is the first. Averroes countered that the existence of the first principle cannot be demonstrated in metaphysics, since such a proof can only begin with God’s effects and with movement in particular. This is why the proof of God belongs to physics. The subject matter of metaphysics is separable beings, among which counts God, as Averroes argues in the Long Commentary on the Physics (ch. I.83, but in other works he assigns this function to being as being; see Bertolacci 2007).