To make this clear, it must be observed that there are two ways in which something is said to be natural to a man; one is according to his specific nature, the other according to his individual nature.  And, since each thing derives its species from its form, and its individuation from matter, and, again, since man’s form is his rational soul, while his matter is his body, whatever belongs to him in respect of his rational soul, is natural to him in respect of his specific nature; while whatever belongs to him in respect of the particular temperament of his body, is natural to him in respect of his individual nature.  For whatever is natural to man in respect of his body, considered as part of his species, is to be referred, in a way, to the soul, in so far as this particular body is adapted to this particular soul.

In both these ways virtue is natural to man inchoatively.  This is so in respect of the specific nature, in so far as in man’s reason are to be found instilled by nature certain naturally known principles of both knowledge and action, which are the nurseries of intellectual and moral virtues, and in so far as there is in the will a natural appetite for good in accordance with reason.  Again, this is so in respect of the individual nature, in so far as by reason of a disposition in the body, some are disposed either well or ill to certain virtues:  because, to wit, certain sensitive powers are acts of certain parts of the body, according to the disposition of which these powers are helped or hindered in the exercise of their acts, and, in consequence, the rational powers also, which the aforesaid sensitive powers assist.  In this way one man has a natural aptitude for science, another for fortitude, another for temperance:  and in these ways, both intellectual and moral virtues are in us by way of a natural aptitude, inchoatively, but not perfectly, since nature is determined to one, while the perfection of these virtues does not depend on one particular mode of action, but on various modes, in respect of the various matters, which constitute the sphere of virtue’s action, and according to various circumstances.

It is therefore evident that all virtues are in us by nature, according to aptitude and inchoation, but not according to perfection, except the theological virtues, which are entirely from without.

This suffices for the Replies to the Objections.  For the first two argue about the nurseries of virtue which are in us by nature, inasmuch as we are rational beings.  The third objection must be taken in the sense that, owing to the natural disposition which the body has from birth, one has an aptitude for pity, another for living temperately, another for some other virtue. ________________________

SECOND ARTICLE [I-II, Q. 63, Art. 2]

Whether Any Virtue Is Caused in Us by Habituation?