• In this paper I will examine Proclus’ Commentary on the First Alcibiades of Plato in order to shed light on his doctrine of the partial soul’s nous. Proclus’ epistemology is in many ways the heart of his system. The human soul is a microcosm, and because each of its faculties corresponds to one or other order of the macrocosm, the soul’s knowledge of reality is primarily through self-knowledge. We have, however, a paradoxical situation in Proclus on this point. On the one hand, he continually relates the doctrines he finds in the texts that he interprets to various psychic or noetic activities, and one sometimes gets the impression that he is more interested in how we grasp a feature of the cosmos than in that feature itself. On the other hand, his epistemological remarks are almost always in passing, and in the context of a discussion of some other point. This paradox is a source of frustration, to this interpreter at least, and leads one to wish dearly that Proclus’ commentaries on Theaetetus and Sophist had survived, where presumably he explained his theory in a more orderly manner.