Chapter 101 — Whether separate substances know all things at the same time by their natural knowledge

Now since the intellect in act is the thing actually understood, as the sense in act is the thing actually sensed, (Aristotle, On the Soul 3.2, 425b22–426a19; 3.5, 430a17–18.) and since the same thing cannot be several things actually at the same time, it would seem impossible for the intellect of a separate substance to have various species of things intelligible, as we have stated above. (Ch. 98.)

But it must be noted that not everything whose intelligible species is actually in the intellect is actually understood. For, since a substance which has understanding also has a will (and consequently has the control of its action), when it already has an intelligible species, it is in its power to make use of it for understanding actually, or, if it have several species, to use one of them. Therefore, we do not actually consider all the things of which we possess knowledge. Therefore, an intellectual substance that has knowledge through several species uses one of them as it will, and thereby knows actually at the same time all that he knows by one species; for they are all as one intelligible thing insofar as they are known through one (species), even as our intellect knows at the same time several things compared or related to one another as one individual thing. But it does not know at the same time the things which it knows through different species. Therefore, as there is one understanding, so is there one thing actually understood.

Accordingly, in the intellect of a separate substance there is a certain succession of understandings: there is not, however, movement properly speaking, since act does not succeed potency, but act succeeds act.

But the divine intellect, because as it knows all things through one (namely, the divine essence), and because its act is its essence, knows all things at the same time.

Consequently, there is no succession in his understanding, but his act of intelligence is wholly perfect at the same time, and endures through all ages. Amen.