Accordingly, those sins which consist in spiritual pleasure, are called spiritual sins; while those which consist in carnal pleasure, are called carnal sins, e.g. gluttony, which consists in the pleasures of the table; and lust, which consists in sexual pleasures.  Hence the Apostle says (2 Cor. 7:1):  “Let us cleanse ourselves from all defilement of the flesh and of the spirit.”

Reply Obj. 1:  As a gloss says on the same passage, these vices are called works of the flesh, not as though they consisted in carnal pleasure; but flesh here denotes man, who is said to live according to the flesh, when he lives according to himself, as Augustine says (De Civ.  Dei xiv, 2, 3).  The reason of this is because every failing in the human reason is due in some way to the carnal sense.

This suffices for the Reply to the Second Objection.

Reply Obj. 3:  Even in the carnal sins there is a spiritual act, viz. the act of reason:  but the end of these sins, from which they are named, is carnal pleasure.

Reply Obj. 4:  As the gloss says, “in the sin of fornication the soul is the body’s slave in a special sense, because at the moment of sinning it can think of nothing else”:  whereas the pleasure of gluttony, although carnal, does not so utterly absorb the reason.  It may also be said that in this sin, an injury is done to the body also, for it is defiled inordinately:  wherefore by this sin alone is man said specifically to sin against his body.  While covetousness, which is reckoned among the carnal sins, stands here for adultery, which is the unjust appropriation of another’s wife.  Again, it may be said that the thing in which the covetous man takes pleasure is something bodily, and in this respect covetousness is numbered with the carnal sins:  but the pleasure itself does not belong to the body, but to the spirit, wherefore Gregory says (Moral. xxxi, 17) that it is a spiritual sin. ________________________

THIRD ARTICLE [I-II, Q. 72, Art. 3]

Whether Sins Differ Specifically in Reference to Their Causes?

Objection 1:  It would seem that sins differ specifically in reference to their causes.  For a thing takes its species from that whence it derives its being.  Now sins derive their being from their causes.  Therefore they take their species from them also.  Therefore they differ specifically in reference to their causes.

Obj. 2:  Further, of all the causes the material cause seems to have least reference to the species.  Now the object in a sin is like its material cause.  Since, therefore, sins differ specifically according to their objects, it seems that much more do they differ in reference to their other causes.