, every mortal sin leads to eternal perdition. But
simple fornication has not this result: because a gloss of Ambrose
[*The quotation is from the Gloss of Peter Lombard, who refers it to
St. Ambrose: whereas it is from Hilary the deacon] on 1 Tim. 4:8,
"Godliness is profitable to all things," says: "The whole of
Christian teaching is summed up in mercy and godliness: if a man
conforms to this, even though he gives way to the inconstancy of the
flesh, doubtless he will be punished, but he will not perish."
Therefore simple fornication is not a mortal sin.

Obj. 6: Further, Augustine says (De Bono Conjug. xvi) that "what food
is to the well-being of the body, such is sexual intercourse to the
welfare of the human race." But inordinate use of food is not always
a mortal sin. Therefore neither is all inordinate sexual intercourse;
and this would seem to apply especially to simple fornication, which
is the least grievous of the aforesaid species.

_On the contrary,_ It is written (Tob. 4:13): "Take heed to keep
thyself . . . from all fornication, and beside thy wife never endure
to know a crime." Now crime denotes a mortal sin. Therefore
fornication and all intercourse with other than one's wife is a
mortal sin.

Further, nothing but mortal sin debars a man from God's kingdom. But
fornication debars him, as shown by the words of the Apostle (Gal.
5:21), who after mentioning fornication and certain other vices,
adds: "They who do such things shall not obtain the kingdom of God."
Therefore simple fornication is a mortal sin.

Further, it is written in the Decretals (XXII, qu. i, can.
Praedicandum): "They should know that the same penance is to be
enjoined for perjury as for adultery, fornication, and wilful murder
and other criminal offenses." Therefore simple fornication is a
criminal or mortal sin.

_I answer that,_ Without any doubt we must hold simple fornication to
be a mortal sin, notwithstanding that a gloss [*St. Augustine, QQ. in
Deut., qu. 37] on Deut. 23:17, says: "This is a prohibition against
going with whores, whose vileness is venial." For instead of "venial"
it should be "venal," since such is the wanton's trade. In order to
make this evident, we must take note that every sin committed
directly against human life is a mortal sin. Now simple fornication
implies an inordinateness that tends to injure the life of the
offspring to be born of this union. For we find in all animals where
the upbringing of the