Aristotle
In Aristotle's philosophy of mind, the passive intellect (nous pathetikos) "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 in On the Soul is very brief, and it has led to dispute as to what it means.
Read more about this topic: Passive Intellect