The Six Books of Proclus on the Theology of Plato, Volume 2

[For if][290] every intellect establishes its essence in eternity, and together with its essence its energy, it will intellectually perceive all things at once. For to every thing which is not established in eternity, the successive objects of its perception subsist according to parts. For every thing which is successive, is in time; the successive consisting of prior and posterior, but the whole of it not existing at once. If therefore all intellects similarly perceive all things,[291] they will not differ from each other. For if they perceive all things similarly,[292] they are similarly all things, since they are the very things which they intellectually perceive. But being similarly all things, one intellect will not be imparticipable, and another not. For their essences are the same things as the objects of their intellection; since the intellection of each is the same with the being of each, and each is both intellection and essence. It remains therefore, either that each intellect does not similarly perceive all things, but one thing, or more than one, but not all things at once; or that it perceives all things according to one.[293] To assert however, that each intellect does not perceive all things, is to make intellect to be ignorant of some particular being.

For if it suffers transition in its energy, and intellectually perceives, not at once, but according to prior and posterior, at the same time possessing an immoveable nature, it will be inferior to soul, which understands all things in being moved, [or in a mutable energy]; because intellect on this hypothesis, will only understand one thing by its permanent energy. It will therefore understand all things according to one. For it either intellectually perceives all things, or one thing, or all things according to the one of intellection. For in all intellects indeed, there is always an intellectual perception of all things; yet so as to bound all things in one of all. Hence there is something predominant in intellection, and the objects of intellection; since all things are at once understood as one, through the domination of one, which characterizes all things with itself.