It is clear, therefore, since we speak of habits and dispositions in respect of a relation to something (Phys. vii, text. 17), that in two ways intensity and remission may be observed in habits and dispositions.  First, in respect of the habit itself:  thus, for instance, we speak of greater or less health; greater or less science, which extends to more or fewer things.  Secondly, in respect of participation by the subject:  in so far as equal science or health is participated more in one than in another, according to a diverse aptitude arising either from nature, or from custom.  For habit and disposition do not give species to the subject:  nor again do they essentially imply indivisibility.

We shall say further on (Q. 66, A. 1) how it is with the virtues.

Reply Obj. 1:  As the word “great” is taken from corporeal quantities and applied to the intelligible perfections of forms; so also is the word “growth,” the term of which is something great.

Reply Obj. 2:  Habit is indeed a perfection, but not a perfection which is the term of its subject; for instance, a term giving the subject its specific being.  Nor again does the nature of a habit include the notion of term, as do the species of numbers.  Wherefore there is nothing to hinder it from being susceptible of more or less.

Reply Obj. 3:  Alteration is primarily indeed in the qualities of the third species; but secondarily it may be in the qualities of the first species:  for, supposing an alteration as to hot and cold, there follows in an animal an alteration as to health and sickness.  In like manner, if an alteration take place in the passions of the sensitive appetite, or the sensitive powers of apprehension, an alteration follows as to science and virtue (Phys. viii, text. 20). ________________________

SECOND ARTICLE [I-II, Q. 52, Art. 2]

Whether Habit Increases by Addition?

Objection 1:  It would seem that the increase of habits is by way of addition.  For the word “increase,” as we have said, is transferred to forms, from corporeal quantities.  But in corporeal quantities there is no increase without addition:  wherefore (De Gener. i, text. 31) it is said that “increase is an addition to a magnitude already existing.”  Therefore in habits also there is no increase without addition.

Obj. 2:  Further, habit is not increased except by means of some agent.  But every agent does something in the passive subject:  for instance, that which heats, causes heat in that which is heated.  Therefore there is no increase without addition.

Obj. 3:  Further, as that which is not white, is in potentiality to be white:  so that which is less white, is in potentiality to be more white.  But that which is not white, is not made white except by the addition of whiteness.  Therefore that which is less white, is not made more white, except by an added whiteness.

On the contrary, The Philosopher says (Phys. iv, text. 84):  “That which is hot is made hotter, without making, in the matter, something hot, that was not hot, when the thing was less hot.”  Therefore, in like manner, neither is any addition made in other forms when they increase.