Reply Obj. 3:  As Cicero says (De Quaest.  Tusc. iv), “disease and sickness are vicious qualities,” for in speaking of the body he calls it disease “when the whole body is infected,” for instance, with fever or the like; he calls it sickness “when the disease is attended with weakness”; and vice “when the parts of the body are not well compacted together.”  And although at times there may be disease in the body without sickness, for instance, when a man has a hidden complaint without being hindered outwardly from his wonted occupations; “yet, in the soul,” as he says, “these two things are indistinguishable, except in thought.”  For whenever a man is ill-disposed inwardly, through some inordinate affection, he is rendered thereby unfit for fulfilling his duties:  since “a tree is known by its fruit,” i.e. man by his works, according to Matt. 12:33.  But “vice of the soul,” as Cicero says (De Quaest.  Tusc. iv), “is a habit or affection of the soul discordant and inconsistent with itself through life”:  and this is to be found even without disease and sickness, e.g. when a man sins from weakness or passion.  Consequently vice is of wider extent than sickness or disease; even as virtue extends to more things than health; for health itself is reckoned a kind of virtue (Phys. vii, text. 17).  Consequently vice is reckoned as contrary to virtue, more fittingly than sickness or disease. ________________________

SECOND ARTICLE [I-II, Q. 71, Art. 2]

Whether Vice Is Contrary to Nature?

Objection 1:  It would seem that vice is not contrary to nature.  Because vice is contrary to virtue, as stated above (A. 1).  Now virtue is in us, not by nature but by infusion or habituation, as stated above (Q. 63, AA. 1, 2, 3).  Therefore vice is not contrary to nature.

Obj. 2:  Further, it is impossible to become habituated to that which is contrary to nature:  thus “a stone never becomes habituated to upward movement” (Ethic. ii, 1).  But some men become habituated to vice.  Therefore vice is not contrary to nature.

Obj. 3:  Further, anything contrary to a nature, is not found in the greater number of individuals possessed of that nature.  Now vice is found in the greater number of men; for it is written (Matt. 7:13):  “Broad is the way that leadeth to destruction, and many there are who go in thereat.”  Therefore vice is not contrary to nature.

Obj. 4:  Further, sin is compared to vice, as act to habit, as stated above (A. 1).  Now sin is defined as “a word, deed, or desire, contrary to the Law of God,” as Augustine shows (Contra Faust. xxii, 27).  But the Law of God is above nature.  Therefore we should say that vice is contrary to the Law, rather than to nature.

On the contrary, Augustine says (De Lib.  Arb. iii, 13):  “Every vice, simply because it is a vice, is contrary to nature.”

I answer that, As stated above (A. 1), vice is contrary to virtue.  Now the virtue of a thing consists in its being well disposed in a manner befitting its nature, as stated above (A. 1).  Hence the vice of any thing consists in its being disposed in a manner not befitting its nature, and for this reason is that thing “vituperated,” which word is derived from “vice” according to Augustine (De Lib.  Arb. iii, 14).