 The reason why Aristotle came to postulate an active intellect was his rejection of Plato’s theory that the essences of sensible things existed apart from matter, in a state of actual intelligibility. For Plato there was clearly no need to posit an active intellect. But Aristotle, who regarded the essences of sensible things as existing in matter with only a potential intelligibility, had to invoke some abstractive principle in the mind itself to render these essences actually intelligible. [In De Anima, bk. 3, lc. 10]