To Florus 6.15

But let us not press the first part of the contest too hard. Let us allow you to proceed in your opinion and prove Adam’s nature good. You surely say: A just God would not impose a law of devotion on a human being if he knew that person suffered a necessity of sinning. If he demanded justice of will from someone he knew to possess an evil nature, he would not prove the transgressor guilty, but publicly show himself an enemy of justice. Yet the just God imposed a law on humanity and promised punishment for transgression. It is therefore established that the human being, good by nature, could sin only by will alone.

You see how sound a conclusion I have offered in your name? It is precisely the sword that flashes in catholic hands and lays waste both Manichaeans and advocates of inherited sin. But I too quickly brought in your party’s name, though for now I wanted my reply taken as yours. The solid response has therefore shaken Mani. I accompany this august reasoning with fitting praise, but notice that the oil of this praise sharpens the sword against you.

Repeat, please, what you said. ‘The just God would not impose a law on humanity if it were evil by nature. But he, being just, imposed a law. It is now clear that humanity could keep what the perfectly fair God commanded, because without the power to obey, the one commanding could never have a reasonable basis for his order.’ What a delightful little argument! Before me, with me as spectator, he establishes the goodness of the nature receiving law from the justice of the lawgiver—and does not see that before Mani feels even a small wound, he has brought destruction upon the advocates of inherited sin.

To make you understand that I seize your bloody weapons while you lie half-dead, and that your dying eyes must bear the sight of victorious truth, I will drive you onto your own weapons. [Literary echo: Virgil, Aeneid 10.462–463.] If the just God could not give Adam a law unless he knew him free to observe justice without any compulsion toward evil, then without doubt the law of later times, carrying the same weight of justice, could not have been given to people if they were born from the womb either weak for good and incapable of justice, or guilty—that is, evil. That later law was also put in writing, more extensive through multiplied provisions, more precise through distinctions, and more fearsome through increased punishment.

For just as the plea of necessity would excuse these people in every transgression, the excessive commands, uncontrolled decrees, and unjust judgments would return as a stain upon their author. Thus this second part closes in the same way as the first. Either you acknowledge that God’s justice could command only what he judged those subject to him could do—in which case the first command destroys Mani, while the later laws destroy Mani and the advocate of inherited sin together—or, if impiety abandons this argument, Mani has not suffered even a slight blow from you. With the world as witness, he will show that he is your father and leader, and that he and you have one single contest against us.