which
words a gloss says that "the law is good, since by forbidding
concupiscence, it forbids all evils," the reason for which is that
concupiscence is the cause of every sin. Now concupiscence is a
distinct passion from love, as stated above (Q. 3, A. 2; Q. 23, A.
4). Therefore self-love is not the cause of every sin.

Obj. 3: Further, Augustine in commenting on Ps. 79:17, "Things set on
fire and dug down," says that "every sin is due either to love
arousing us to undue ardor or to fear inducing false humility."
Therefore self-love is not the only cause of sin.

Obj. 4: Further, as man sins at times through inordinate love of
self, so does he sometimes through inordinate love of his neighbor.
Therefore self-love is not the cause of every sin.

_On the contrary,_ Augustine says (De Civ. Dei xiv, 28) that
"self-love, amounting to contempt of God, builds up the city of
Babylon." Now every sin makes man a citizen of Babylon. Therefore
self-love is the cause of every sin.

_I answer that,_ As stated above (Q. 75, A. 1), the proper and direct
cause of sin is to be considered on the part of the adherence to a
mutable good; in which respect every sinful act proceeds from
inordinate desire for some temporal good. Now the fact that anyone
desires a temporal good inordinately, is due to the fact that he
loves himself inordinately; for to wish anyone some good is to love
him. Therefore it is evident that inordinate love of self is the
cause of every sin.

Reply Obj. 1: Well ordered self-love, whereby man desires a fitting
good for himself, is right and natural; but it is inordinate
self-love, leading to contempt of God, that Augustine (De Civ. Dei
xiv, 28) reckons to be the cause of sin.

Reply Obj. 2: Concupiscence, whereby a man desires good for himself,
is reduced to self-love as to its cause, as stated.

Reply Obj. 3: Man is said to love both the good he desires for
himself, and himself to whom he desires it. Love, in so far as it is
directed to the object of desire (e.g. a man is said to love wine or
money) admits, as its cause, fear which pertains to avoidance of
evil: for every sin arises either from inordinate desire for some
good, or from inordinate avoidance of some evil. But each of these is
reduced to self-love, since it is through loving himself that man
either desires good things, or avoids evil things.

Reply Obj. 4: A friend is like another self (Ethic. ix): wherefore
the sin which is committed through l