Lactantius, Divine Institutes 6.23

I turn now to the pleasure that comes through touch, a sense that belongs to the whole body, but I will speak not of ornaments or clothing; I will speak of lust alone, because it must be restrained above all else, since it does the greatest harm.

When God had devised the rationale for the two sexes, He gave them a mutual longing and a joy in their union, and so He planted in the bodies of all living creatures a most ardent desire, so that they would rush eagerly into these affections and, for that reason, the kinds might be propagated and multiplied.

This desire and striving is found in human beings more vehement and keen, either because God willed a greater multitude of humankind or because He gave virtue to humanity alone, so that there would be praise and glory in restraining pleasures and in self‑abstinence.

Our adversary therefore knows well the power of this desire, which some have preferred to call necessity, and he twists it from what is right and good into what is wrong and evil.

He injects illicit desires so that they may defile what belongs to another, even though it is permitted to have one's own without fault; he parades irresistible forms before the eyes, suggests incitements, and supplies fuel to vices; then deep in the innermost parts he stirs up every goad, agitates them, kindles and inflames that natural ardor, until he deceives the man who has been snared and entangled.

And lest anyone should abstain from another's body out of fear of punishment, he also established brothels and exposed the shame of wretched women, so that he might hold up as a mockery both those who do the deed and those who are forced to suffer it.

By these obscenities he has plunged souls born for sanctity, as it were, into a whirlpool of mud, extinguished shame, and ravaged chastity.

He has joined males with males and contrived unspeakable unions contrary to nature and contrary to God's institution, and thus he has steeped men in wickedness and armed them for every evil.

What can be holy for those who hand over their weak and defenseless years to their lust to be ravaged and defiled? This crime cannot be described in terms adequate to its magnitude.

I can call them nothing but impious and parricides, for whom the sex given by God does not suffice, unless they also profane and wantonly mock their own sex; yet among them these things are regarded as light and almost honorable.

What shall I say of those who practice not detestable lust but sheer insanity? It revolts me to speak of it, but what do we suppose will become of those who feel no revulsion in doing it?

And yet it must be spoken, because it happens: I speak of those whose foulest lust and execrable fury does not spare even the head; with what words or what indignation shall I pursue so great a crime? The enormity of the crime silences the tongue.

Therefore, since this lust produces such works and designs such crimes, we must arm ourselves against it with the greatest virtue.

Whoever cannot restrain those affections must keep them within the bounds of the legitimate marriage bed, so that he may obtain what he eagerly seeks and yet not fall into sin.

For what do the lost not desire? Indeed, pleasure follows honorable works; if they pursue pleasure for its own sake, it is permitted to enjoy it justly and lawfully.

But if some necessity makes its claim, then virtue must be applied all the more, so that continence may resist desire.

Nor is it only forbidden to touch the marriage beds of others; God also commands and teaches us to abstain from public and common bodies, so that when two bodies have been joined together they become one body.