A. 3), a capital vice
denotes one from which, considered as final cause, i.e. as having a
most desirable end, other vices originate: wherefore through desiring
that end men are incited to sin in many ways. Now an end is rendered
most desirable through having one of the conditions of happiness
which is desirable by its very nature: and pleasure is essential to
happiness, according to _Ethic._ i, 8; x, 3, 7, 8. Therefore the vice
of gluttony, being about pleasures of touch which stand foremost
among other pleasures, is fittingly reckoned among the capital vices.

Reply Obj. 1: It is true that food itself is directed to something as
its end: but since that end, namely the sustaining of life, is most
desirable and whereas life cannot be sustained without food, it
follows that food too is most desirable: indeed, nearly all the toil
of man's life is directed thereto, according to Eccles. 6:7, "All the
labor of man is for his mouth." Yet gluttony seems to be about
pleasures of food rather than about food itself; wherefore, as
Augustine says (De Vera Relig. liii), "with such food as is good for
the worthless body, men desire to be fed," wherein namely the
pleasure consists, "rather than to be filled: since the whole end of
that desire is this--not to thirst and not to hunger."

Reply Obj. 2: In sin the end is ascertained with respect to the
conversion, while the gravity of sin is determined with regard to the
aversion. Wherefore it does not follow that the capital sin which has
the most desirable end surpasses the others in gravity.

Reply Obj. 3: That which gives pleasure is desirable in itself: and
consequently corresponding to its diversity there are two capital
vices, namely gluttony and lust. On the other hand, that which is
useful is desirable, not in itself, but as directed to something
else: wherefore seemingly in all useful things there is one aspect of
desirability. Hence there is but one capital vice, in respect of such
things.
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SIXTH ARTICLE [II-II, Q. 148, Art. 6]

Whether [Five] Daughters Are Fittingly Assigned to Gluttony?

Objection 1: It would seem that [five] daughters are unfittingly
assigned to gluttony, to wit, "unseemly joy, scurrility, uncleanness,
loquaciousness, and dullness of mind as regards the understanding."
For unseemly joy results from every sin, according to Prov. 2:14,
"Who are glad when they have done evil, and rejoice in most wicked
things." Likewise dullness