Proverbs 6:28

And concerning chastity, the holy word teaches us not only not to sin in act, but not even in thought, not even in the heart to think of any evil, nor look on another man’s wife with our eyes to lust after her. Solomon, accordingly, who was a king and a prophet, said: “Let thine eyes look right on, and let thine eyelids look straight before thee: make straight paths for your feet.” And the voice of the Gospel teaches still more urgently concerning chastity, saying: “Whosoever looketh on a woman who is not his own wife, to lust after her, hath committed adultery with her already in his heart.” “And he that marrieth,” says [the Gospel], “her that is divorced from her husband, committeth adultery; and whosoever putteth away his wife, saving for the cause of fornication, causeth her to commit adultery.” Because Solomon says: “Can a man take fire in his bosom, and his clothes not be burned? O …

14. I blush to speak of it, it is so shocking; yet though sad, it is true. How comes this plague of the agapetæ to be in the church? Whence come these unwedded wives, these novel concubines, these harlots, so I will call them, though they cling to a single partner? One house holds them and one chamber. They often occupy the same bed, and yet they call us suspicious if we fancy anything amiss. A brother leaves his virgin sister; a virgin, slighting her unmarried brother, seeks a brother in a stranger. Both alike profess to have but one object, to find spiritual consolation from those not of their kin; but their real aim is to indulge in sexual intercourse. It is on such that Solomon in the book of proverbs heaps his scorn. “Can a man take fire in his bosom,” he says, “and his clothes not be burned? Can one go upon hot coals and his feet not be burned?”

7. Among other things the Corinthians asked in their letter whether after embracing the faith of Christ they ought to be unmarried, and for the sake of continence put away their wives, and whether believing virgins were at liberty to marry. And again, supposing that one of two Gentiles believed on Christ, whether the one that believed should leave the one that believed not? And in case it were allowable to take wives, would the Apostle direct that only Christian wives, or Gentiles also, should be taken? Let us then consider Paul’s replies to these inquiries.“Now concerning the things whereof ye wrote: It is good for a man not to touch a woman. But, because of fornications, let each man have his own wife, and let each woman have her own husband. Let the husband render unto the wife her due: and likewise also the wife unto the husband. …

75. Let us also pass over this fire of lust, fearing which Paul, but fearing for us, inasmuch as by buffeting his body he had come no longer to fear for himself, says to us: “Flee fornication.” Let us then flee it as though following us, though indeed it follows not behind us, but within our very selves. Let us then diligently take heed lest while we are fleeing from it we carry it with ourselves. For we wish for the most part to flee, but if we do not wholly cast it out of our mind, we rather take it up than forsake it. Let us then spring over it, lest it be said to us: “Walk ye in the flame of your fire, which ye have kindled for yourselves.” For as he who “takes fire into his bosom burns his clothes,” so he who walks upon fiery coals must of necessity burn his feet, as it is written: “Can one walk upon coals of fire and not burn his feet?”