Memory is of past things. But the past is referred to by reference to a definite time. Memory therefore is a way of knowing things in reference to a definite time, which is to say that it knows things by reference to here and now. But such knowledge is the province of the senses, not of intellect. So memory belongs not to the intellectual part of the soul, but to the same part as the senses.

[W]e can […] come to know the human soul’s mode of existence, on the basis of its activity. For insofar as it has an activity [viz., intellective cognition] that transcends material things, its existence, too, is raised above the body and does not depend on it. On the other hand, insofar as it is naturally suited to acquire immaterial cognition from what is material, the fulfilment of its nature clearly cannot occur without union with the body; for something is complete in its nature only if it has [in itself] the things that are required for the activity that is proper to its nature. Therefore, since the human soul, insofar as it is united to the body as a form, also has its existence raised above the body and does not depend on it, it is clear that the soul is established on the borderline between corporeal and separate [i.e., purely spiritual] substances.