To Florus 5.23

Let us now pursue what the passage requires. It is clear, most subtle debater, that you have exalted one and the same thing—human nature—with great praises, but stained it with still greater accusations. Just as these cannot occur together at one time, in one work, and under one intention, so natural reason cannot admit them even as alternating opposites. Nature always possesses one full valuation, namely goodness. It is never attacked for evil—which its institutions, because of its maker’s dignity, do not admit—except by the utterly filthy teeth of the Manichaeans.

Having completed this point, I ask what wisps of marriage you think you should pursue. If you confess that the cause of a human being is not marriage but nature, and the cause of sin too is not marriage but nature, then the marriage you were praising has entirely vanished. To what effect is it assigned if it is the cause of neither your evil nor my good? You remove the human being from marriage’s honorable activity lest you be compelled to attribute him to fornication too. You remove sin from marriage’s necessary activity lest you appear to condemn marriage. What remains worthy of praise in marriage’s possession? Why fear to violate with a word what you have utterly demolished by argument? Of what will it be called the cause if it shares in neither natural evil nor natural good? Do the name and honor of marriage now accomplish nothing in human affairs?

But you are choking, and painfully. We must therefore help the panting old man. Something remains you can give marriage, without which nothing else is found: say that marriage stands guard at the door, allowing no report of obscenity to burst in upon the partners’ pleasure, but claiming honor and modesty for that activity under its own title. Your attempt to corrupt marriage’s integrity with deceitful praise was therefore pointless. It is more hostile to no one than to you. It drives you utterly away and does not allow Manichaean tongues to creep in and lacerate the union entrusted to its protection. ‘They have brothels worthy of their doctrine,’ it says, ‘where they may satisfy themselves at night.’ Marriage’s watch guards the pleasure of modest people; crimes are barred and the honor of decency admitted. The privileges the apostle granted defend honorable marriage and undefiled beds; ‘but God will judge fornicators and adulterers’ (Hebrews 13:4). Where, then, is the criminal union, if the authority of the marriage you praised serves its activity and privacy?