THIRD ARTICLE [II-II, Q. 153, Art. 3]

Whether the Lust That Is About Venereal Acts Can Be a Sin?

Objection 1: It would seem that lust about venereal acts cannot be a

sin. For the venereal act consists in the emission of semen which is

the surplus from food, according to the Philosopher (De Gener. Anim.

i, 18). But there is no sin attaching to the emission of other

superfluities. Therefore neither can there be any sin in venereal

acts.

Obj. 2: Further, everyone can lawfully make what use he pleases of

what is his. But in the venereal act a man uses only what is his own,

except perhaps in adultery or rape. Therefore there can be no sin in

venereal acts, and consequently lust is no sin.

Obj. 3: Further, every sin has an opposite vice. But, seemingly, no

vice is opposed to lust. Therefore lust is not a sin.

_On the contrary,_ The cause is more powerful than its effect. Now

wine is forbidden on account of lust, according to the saying of the

Apostle (Eph. 5:18), "Be not drunk with wine wherein is lust [Douay:

'luxury']." Therefore lust is forbidden.

Further, it is numbered among the works of the flesh: Gal. 5:19

[Douay: 'luxury'].

_I answer that,_ The more necessary a thing is, the more it behooves

one to observe the order of reason in its regard; wherefore the more

sinful it becomes if the order of reason be forsaken. Now the use of

venereal acts, as stated in the foregoing Article, is most necessary

for the common good, namely the preservation of the human race.

Wherefore there is the greatest necessity for observing the order of

reason in this matter: so that if anything be done in this connection

against the dictate of reason's ordering, it will be a sin. Now lust

consists essentially in exceeding the order and mode of reason in the

matter of venereal acts. Wherefore without any doubt lust is a sin.

Reply Obj. 1: As the Philosopher says in the same book (De Gener.

Anim. i, 18), "the semen is a surplus that is needed." For it is said

to be superfluous, because it is the residue from the action of the

nutritive power, yet it is needed for the work of the generative

power. But the other superfluities of the human body are such as not

to be needed, so that it matters not how they are emitted, provided

one observe the decencies of social life. It is different with the

emission of semen, which should be accomplished in a manner befitting

the end for which it is needed.

Reply Obj. 2: As the Apostle says (1 Cor. 6:20) in speaking against

lust, "You are bought with a great price: glorify and bear God in

your body." Wherefore by inordinately using the body through lust a

man wrongs God Who is the Supreme Lord of our body. Hence Augustine

says (De Decem. Chord. 10 [*Serm. ix (xcvi de Temp.)]): "God Who thus

governs His servants for their good, not for His, made this order and

commandment, lest unlawful pleasures should destroy His temple which

thou hast begun to be."

Reply Obj. 3: The opposite of lust is not found in many, since men

are more inclined to pleasure. Yet the contrary vice is comprised

under insensibility, and occurs in one who has such a dislike for

sexual intercourse as not to pay the marriage debt.

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Summa Theologica, Part II-II (Secunda Secundae) Translated by Fathers of the English Dominican Province · 第 914 / 1128 题