e; and so on. Nor is there any difficulty in the intellect being
thus potentially infinite, as explained above (Q. 86, A. 2).

Reply Obj. 3: The proper sense feels by reason of the immutation in
the material organ caused by the external sensible. A material
object, however, cannot immute itself; but one is immuted by another,
and therefore the act of the proper sense is perceived by the common
sense. The intellect, on the contrary, does not perform the act of
understanding by the material immutation of an organ; and so there
is no comparison.
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FOURTH ARTICLE [I, Q. 87, Art. 4]

Whether the Intellect Understands the Act of the Will?

Objection 1: It would seem that the intellect does not understand the
act of the will. For nothing is known by the intellect, unless it be
in some way present in the intellect. But the act of the will is not
in the intellect; since the will and the intellect are distinct.
Therefore the act of the will is not known by the intellect.

Obj. 2: Further, the act is specified by the object. But the object
of the will is not the same as the object of the intellect. Therefore
the act of the will is specifically distinct from the object of the
intellect, and therefore the act of the will is not known by the
intellect.

Obj. 3: Augustine (Confess. x, 17) says of the soul's affections that
"they are known neither by images as bodies are known; nor by their
presence, like the arts; but by certain notions." Now it does not
seem that there can be in the soul any other notions of things but
either the essences of things known or the likenesses thereof.
Therefore it seems impossible for the intellect to known such
affections of the soul as the acts of the will.

_On the contrary,_ Augustine says (De Trin. x, 11), "I understand
that I will."

_I answer that,_ As stated above (Q. 59, A. 1), the act of the will
is nothing but an inclination consequent on the form understood; just
as the natural appetite is an inclination consequent on the natural
form. Now the inclination of a thing resides in it according to its
mode of existence; and hence the natural inclination resides in a
natural thing naturally, and the inclination called the sensible
appetite is in the sensible thing sensibly; and likewise the
intelligible inclination, which is the act of the will, is in the
intelligent subject intelligibly as in its principle and proper
subject. Hence the Philosopher expresses himsel