l those things from which it abstracts the
universal, with respect to which things the universal is one. And
this befits the active intellect inasmuch as it is immaterial.

Reply Obj. 3: All things which are of one species enjoy in common the
action which accompanies the nature of the species, and consequently
the power which is the principle of such action; but not so as that
power be identical in all. Now to know the first intelligible
principles is the action belonging to the human species. Wherefore
all men enjoy in common the power which is the principle of this
action: and this power is the active intellect. But there is no need
for it to be identical in all. Yet it must be derived by all from one
principle. And thus the possession by all men in common of the first
principles proves the unity of the separate intellect, which Plato
compares to the sun; but not the unity of the active intellect, which
Aristotle compares to light.
_______________________

SIXTH ARTICLE [I, Q. 79, Art. 6]

Whether Memory Is in the Intellectual Part of the Soul?

Objection 1: It would seem that memory is not in the intellectual
part of the soul. For Augustine says (De Trin. xii, 2,3,8) that to
the higher part of the soul belongs those things which are not
"common to man and beast." But memory is common to man and beast,
for he says (De Trin. xii, 2, 3, 8) that "beasts can sense corporeal
things through the senses of the body, and commit them to memory."
Therefore memory does not belong to the intellectual part of the
soul.

Obj. 2: Further, memory is of the past. But the past is said of
something with regard to a fixed time. Memory, therefore, knows a
thing under a condition of a fixed time; which involves knowledge
under the conditions of "here" and "now." But this is not the
province of the intellect, but of the sense. Therefore memory is
not in the intellectual part, but only in the sensitive.

Obj. 3: Further, in the memory are preserved the species of those
things of which we are not actually thinking. But this cannot happen
in the intellect, because the intellect is reduced to act by the fact
that the intelligible species are received into it. Now the intellect
in act implies understanding in act; and therefore the intellect
actually understands all things of which it has the species.
Therefore the memory is not in the intellectual part.

_On the contrary,_ Augustine says (De Trin. x, 11) that "memory,
understanding, an