considering, is able to consider. In the second place, this
supposition is contrary to the truth. For as to whom belongs the
operation, belongs also the power to operate, belongs also the habit.
But to understand and to consider is the proper act of the intellect.
Therefore also the habit whereby one considers is properly in the
intellect itself.

Reply Obj. 1: Some said, as Simplicius reports in his
_Commentary on the Predicaments,_ that, since every operation of man is
to a certain extent an operation of the _conjunctum,_ as the
Philosopher says (De Anima i, text. 64); therefore no habit is in the
soul only, but in the _conjunctum._ And from this it follows that no
habit is in the intellect, for the intellect is separate, as ran the
argument, given above. But the argument is not cogent. For habit is not
a disposition of the object to the power, but rather a disposition of
the power to the object: wherefore the habit needs to be in that power
which is principle of the act, and not in that which is compared to
the power as its object.

Now the act of understanding is not said to be common to soul and
body, except in respect of the phantasm, as is stated in _De Anima_,
text. 66. But it is clear that the phantasm is compared as object to
the passive intellect (De Anima iii, text. 3, 39). Whence it follows
that the intellective habit is chiefly on the part of the intellect
itself; and not on the part of the phantasm, which is common to soul
and body. And therefore we must say that the "possible" intellect is
the subject of habit, which is in potentiality to many: and this
belongs, above all, to the "possible" intellect. Wherefore the
"possible" intellect is the subject of intellectual habits.

Reply Obj. 2: As potentiality to sensible being belongs to
corporeal matter, so potentiality to intellectual being belongs to the
"possible" intellect. Wherefore nothing forbids habit to be in the
"possible" intellect, for it is midway between pure potentiality and
perfect act.

Reply Obj. 3: Because the apprehensive powers inwardly prepare
their proper objects for the _possible intellect,_ therefore it is by
the good disposition of these powers, to which the good disposition of
the body cooperates, that man is rendered apt to understand. And so in
a secondary way the intellective habit can be in these powers. But
principally it is in the "possible" intellect.
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FIFTH ARTICLE [I-II, Q. 50, Art. 5]