s place through some kind of
similitude, he thought that the form of the thing known must of
necessity be in the knower in the same manner as in the thing known.
Then he observed that the form of the thing understood is in the
intellect under conditions of universality, immateriality, and
immobility: which is apparent from the very operation of the
intellect, whose act of understanding has a universal extension, and
is subject to a certain amount of necessity: for the mode of action
corresponds to the mode of the agent's form. Wherefore he concluded
that the things which we understand must have in themselves an
existence under the same conditions of immateriality and immobility.

But there is no necessity for this. For even in sensible things it is
to be observed that the form is otherwise in one sensible than in
another: for instance, whiteness may be of great intensity in one,
and of a less intensity in another: in one we find whiteness with
sweetness, in another without sweetness. In the same way the sensible
form is conditioned differently in the thing which is external to the
soul, and in the senses which receive the forms of sensible things
without receiving matter, such as the color of gold without receiving
gold. So also the intellect, according to its own mode, receives
under conditions of immateriality and immobility, the species of
material and mobile bodies: for the received is in the receiver
according to the mode of the receiver. We must conclude, therefore,
that through the intellect the soul knows bodies by a knowledge which
is immaterial, universal, and necessary.

Reply Obj. 1: These words of Augustine are to be understood as
referring to the medium of intellectual knowledge, and not to its
object. For the intellect knows bodies by understanding them, not
indeed through bodies, nor through material and corporeal species;
but through immaterial and intelligible species, which can be in the
soul by their own essence.

Reply Obj. 2: As Augustine says (De Civ. Dei xxii, 29), it is not
correct to say that as the sense knows only bodies so the intellect
knows only spiritual things; for it follows that God and the angels
would not know corporeal things. The reason of this diversity is that
the lower power does not extend to those things that belong to the
higher power; whereas the higher power operates in a more excellent
manner those things which belong to the lower power.

Reply Obj. 3: Every movement