The passive intellect (Latin: intellectus possibilis; also translated as potential intellect or material intellect), is a term used in philosophy alongside the notion of the active intellect in order to give an account of the operation of the intellect (nous), in accordance with the theory of hylomorphism, as most famously put forward by Aristotle.
Aristotle gives his most substantial account of the passive intellect (nous pathetikos) in De Anima (On the Soul), Book III, chapter 4. In Aristotle's philosophy of mind, the passive intellect "is what it is by becoming all things." By this Aristotle means that the passive intellect can potentially become anything by receiving that thing's intelligible form. The active intellect (nous poietikos) is then required to illuminate the passive intellect to make the potential knowledge into knowledge in act, in the same way that light makes potential colors into actual colors. The analysis of this distinction is very brief, which has led to dispute as to what it means.
Greek thought
While Greek commentators such as Alexander of Aphrodisias and Themistius were broadly silent on the active intellect (debate over this would only become heated in the thirteenth-century Christian West in the context of debates over whether Avicenna or Averroes provided the account of the working of the intellect that best cohered with Christian doctrine), they provided a great deal of commentary on the nature of the passive intellect. For Alexander of Aphrodisias, for instance, (who coined the term of the 'material intellect' for this power, a name later taken up by Averroes), the passive intellect was a separate intellect from the active.