In this paper I argue that Proclus’ criticism of the causality of Aristotle’s intellect is part of a general attack on Aristotle’s metaphysics. I show how Proclus criticises Aristotle for rejecting the One as a metaphysical principle and the metaphysical confusion that arises from this. Additionally, I claim that for Proclus Aristotle’s understanding of efficient causality differs from Plato’s and I discuss two of his arguments that Aristotle should have accepted the intellect as an efficient cause. As I show throughout, (...) Proclus differs in his approach to Aristotle from the harmonising agenda of Ammonius and Simplicius. (shrink)