covetousness is the most grievous of sins.

Obj. 4: Further, the Apostle says (Eph. 5:5) that covetousness is "a
serving of idols." Now idolatry is reckoned among the most grievous
sins. Therefore covetousness is also.

_On the contrary,_ Adultery is a more grievous sin than theft,
according to Prov. 6:30. But theft pertains to covetousness.
Therefore covetousness is not the most grievous of sins.

_I answer that,_ Every sin, from the very fact that it is an evil,
consists in the corruption or privation of some good: while, in so
far as it is voluntary, it consists in the desire of some good.
Consequently the order of sins may be considered in two ways. First,
on the part of the good that is despised or corrupted by sin, and
then the greater the good the graver the sin. From this point of view
a sin that is against God is most grievous; after this comes a sin
that is committed against a man's person, and after this comes a sin
against external things, which are deputed to man's use, and this
seems to belong to covetousness. Secondly, the degrees of sin may be
considered on the part of the good to which the human appetite is
inordinately subjected; and then the lesser the good, the more
deformed is the sin: for it is more shameful to be subject to a lower
than to a higher good. Now the good of external things is the lowest
of human goods: since it is less than the good of the body, and this
is less than the good of the soul, which is less than the Divine
good. From this point of view the sin of covetousness, whereby the
human appetite is subjected even to external things, has in a way a
greater deformity. Since, however, corruption or privation of good is
the formal element in sin, while conversion to a mutable good is the
material element, the gravity of the sin is to be judged from the
point of view of the good corrupted, rather than from that of the
good to which the appetite is subjected. Hence we must assert that
covetousness is not simply the most grievous of sins.

Reply Obj. 1: These authorities speak of covetousness on the part of
the good to which the appetite is subjected. Hence (Ecclus. 10:10) it
is given as a reason that the covetous man "setteth his own soul to
sale"; because, to wit, he exposes his soul--that is, his life--to
danger for the sake of money. Hence the text continues: "Because
while he liveth he hath cast away"--that is, despised--"his bowels,"
in order to make money. Tully also adds that