De Decalogo

inasmuch as it not only persuades the adulterer to commit iniquity, but also teaches him to join others in wickedness, making an association in things in which there ought to be no such participation. For when this violent passion seizes on a man it is impossible for the appetites to arrive at the accomplishment of their object by one person alone, but it is indispensable that two should share in the action, the one taking the place of the teacher, and the other that of the pupil, for the complete confirmation of those most disgraceful evils, intemperance and licentiousness.

Nor can one allege as an excuse that it is only the body of the woman who is committing adultery that is corrupted, but, if one must tell the truth, even before the corruption of the body the soul is accustomed to alienation from virtue, being taught in every way to repudiate and to hate its husband.