ion of the intellect. Therefore there
is no interior power between the sense and intellect, besides the
imagination.

_On the contrary,_ Avicenna (De Anima iv, 1) assigns five interior
sensitive powers; namely, "common sense, phantasy, imagination, and
the estimative and memorative powers."

_I answer that,_ As nature does not fail in necessary things, there
must needs be as many actions of the sensitive soul as may suffice
for the life of a perfect animal. If any of these actions cannot be
reduced to the same one principle, they must be assigned to diverse
powers; since a power of the soul is nothing else than the proximate
principle of the soul's operation.

Now we must observe that for the life of a perfect animal, the animal
should apprehend a thing not only at the actual time of sensation, but
also when it is absent. Otherwise, since animal motion and action
follow apprehension, an animal would not be moved to seek something
absent: the contrary of which we may observe specially in perfect
animals, which are moved by progression, for they are moved towards
something apprehended and absent. Therefore an animal through the
sensitive soul must not only receive the species of sensible things,
when it is actually affected by them, but it must also retain and
preserve them. Now to receive and retain are, in corporeal things,
reduced to diverse principles; for moist things are apt to receive,
but retain with difficulty, while it is the reverse with dry things.
Wherefore, since the sensitive power is the act of a corporeal organ,
it follows that the power which receives the species of sensible
things must be distinct from the power which preserves them.

Again we must observe that if an animal were moved by pleasing and
disagreeable things only as affecting the sense, there would be no
need to suppose that an animal has a power besides the apprehension of
those forms which the senses perceive, and in which the animal takes
pleasure, or from which it shrinks with horror. But the animal needs
to seek or to avoid certain things, not only because they are pleasing
or otherwise to the senses, but also on account of other advantages
and uses, or disadvantages: just as the sheep runs away when it sees a
wolf, not on account of its color or shape, but as a natural enemy:
and again a bird gathers together straws, not because they are
pleasant to the sense, but because they are useful for building its
nest. Animals, therefore,