Now, in the first place, this supposition is contrary to the mind of Aristotle.  For it is manifest that the sensitive powers are rational, not by their essence, but only by participation (Ethic. i, 13).  Now the Philosopher puts the intellectual virtues, which are wisdom, science and understanding, in that which is rational by its essence.  Wherefore they are not in the sensitive powers, but in the intellect itself.  Moreover he says expressly (De Anima iii, text. 8, 18) that when the “possible” intellect “is thus identified with each thing,” that is, when it is reduced to act in respect of singulars by the intelligible species, “then it is said to be in act, as the knower is said to be in act; and this happens when the intellect can act of itself,” i.e. by considering:  “and even then it is in potentiality in a sense; but not in the same way as before learning and discovering.”  Therefore the “possible” intellect itself is the subject of the habit of science, by which the intellect, even though it be not actually 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.