Whether no venereal act can be without sin?

Objections

Objection 1 : It would seem that no venereal act can be without sin. For nothing but sin would seem to hinder virtue. Now every venereal act is a great hindrance to virtue. For Augustine says (Soliloq. i, 10): "I consider that nothing so casts down the manly mind from its height as the fondling of a woman, and those bodily contacts." Therefore, seemingly, no venereal act is without sin.
Objection 2 : Further, any excess that makes one forsake the good of reason is sinful, because virtue is corrupted by "excess" and "deficiency" as stated in Ethic. ii, 2. Now in every venereal act there is excess of pleasure, since it so absorbs the mind, that "it is incompatible with the act of understanding," as the Philosopher observes (Ethic. vii, 11); and as Jerome [*Origen, Hom. vi in Num.; Cf. Jerome, Ep. cxxiii ad Ageruch.] states, rendered the hearts of the prophets, for the moment, insensible to the spirit of prophecy. Therefore no venereal act can be without sin.
Objection 3 : Further, the cause is more powerful than its effect. Now original sin is transmitted to children by concupiscence, without which no venereal act is possible, as Augustine declares (De Nup. et Concup. i, 24). Therefore no venereal act can be without sin.