  His primary investigation of mind occurs in two chapters of De Anima, both of which are richly suggestive, but neither of which admits of easy or uncontroversial exposition. In De Anima iii 4 and 5, Aristotle approaches the nature of thinking by once again deploying a hylomorphic analysis, given in terms of form reception. Just as perception involves the reception of a sensible form by a suitably qualified sensory faculty, so thinking involves the reception of an intelligible form by a suitably qualified intellectual faculty (De Anima iii 4, 429a13–18). According to this model, thinking consists in a mind’s becoming enformed by some object of thought, so that actual thinking occurs whenever some suitably prepared mind is “made like” its object by being affected by it.