Ia IIae q. 88 a. 1
Whether venial sin is fttingly condivided with mortal sin?
It would seem that venial sin is unfttingly
condivided with mortal sin. For Augustine says (Contra Faust.
xxii, 27): “Sin is a word, deed or desire contrary to the eternal
law.” But the ±act o± being against the eternal law makes a sin to
be mortal. Consequently every sin is mortal. ere±ore venial
sin is not condivided with mortal sin.
Further, the Apostle says (1 Cor. 10:31):
“Whether you eat or drink, or whatever else you do; do all to
the glory o± God.” Now whoever sins breaks this command-
ment, because sin is not done ±or God’s glory. Consequently,
since to break a commandment is to commit a mortal sin, it
seems that whoever sins, sins mortally.
Further, whoever cleaves to a thing by love,
cleaves either as enjoying it, or as using it, as Augustine states
(De Doctr. Christ. i, 3,4). But no person, in sinning, cleaves to
a mutable good as using it: because he does not re±er it to that
good which gives us happiness, which, properly speaking, is to
use, according to Augustine (De Doctr. Christ. i, 3,4). ere-
±ore whoever sins enjoys a mutable good. Now “to enjoy what
we should use is human perverseness,” as Augustine again says
(Qq. lxxxiii, qu. 30). ere±ore, since “perverseness”
a mortal sin, it seems that whoever sins, sins mortally.
Further, whoever approaches one term, ±rom
that very ±act turns away ±rom the opposite. Now whoever
sins, approaches a mutable good, and, consequently turns away
±rom the immutable good, so that he sins mortally. ere±ore