and if it goes so far as to be firmly fixed and to become difficult to change, then it will be a habit:  so that disposition would be a certain intensity of passion or passion-like quality, and habit an intensity or disposition.  But Simplicius disapproves of this, for such intensity and remissness do not imply diversity on the part of the form itself, but on the part of the diverse participation thereof by the subject; so that there would be no diversity among the species of quality.  And therefore we must say otherwise that, as was explained above (Q. 49, A. 2, ad 1), the adjustment of the passion-like qualities themselves, according to their suitability to nature, implies the notion of disposition:  and so, when a change takes place in these same passion-like qualities, which are heat and cold, moisture and dryness, there results a change as to sickness and health.  But change does not occur in regard to like habits and dispositions, primarily and of themselves. ________________________

SECOND ARTICLE [I-II, Q. 50, art. 2]

Whether the Soul Is the Subject of Habit in Respect of Its Essence or in Respect of Its Power?

Objection 1:  It would seem that habit is in the soul in respect of its essence rather than in respect of its powers.  For we speak of dispositions and habits in relation to nature, as stated above (Q. 49, A. 2).  But nature regards the essence of the soul rather than the powers; because it is in respect of its essence that the soul is the nature of such a body and the form thereof.  Therefore habits are in the soul in respect of its essence and not in respect of its powers.

Obj. 2:  Further, accident is not the subject of accident.  Now habit is an accident.  But the powers of the soul are in the genus of accident, as we have said in the First Part (Q. 77, A. 1, ad 5).  Therefore habit is not in the soul in respect of its powers.

Obj. 3:  Further, the subject is prior to that which is in the subject.  But since habit belongs to the first species of quality, it is prior to power, which belongs to the second species.  Therefore habit is not in a power of the soul as its subject.

On the contrary, The Philosopher (Ethic. i, 13) puts various habits in the various powers of the soul.

I answer that, As we have said above (Q. 49, AA. 2, 3), habit implies a certain disposition in relation to nature or to operation.  If therefore we take habit as having a relation to nature, it cannot be in the soul—­that is, if we speak of human nature:  for the soul itself is the form completing the human nature; so that, regarded in this way, habit or disposition is rather to be found in the body by reason of its relation to the soul, than in the soul by reason of its relation to the body.  But if we speak of a higher nature, of which man may become a partaker, according to 2 Pet. 1, “that we may be partakers of the Divine Nature”:  thus nothing hinders some habit, namely, grace, from being in the soul in respect of its essence, as we shall state later on (Q. 110, A. 4).