To Florus 5.17

Since enough has been said about this, let us hasten to the arguments Mani once cleverly advanced concerning natural evil—although, as I shall prove, he was deceived by tangled questions. First, however, let us briefly examine what Augustine replied to the apostle’s testimony. I had said that blessed Paul’s testimony proved most clearly that God, the creator of bodies, instituted the familiar activity of the sexes. Denouncing the shameful acts of those whose madness had plunged them even into intercourse with the male sex, Paul says: ‘Abandoning the natural use of the female, they burned in their own desires’ (Romans 1:27). I inferred, with the apostle as witness, that intercourse with the female is shown to have been naturally instituted.

In response this man writes: ‘The apostle did not say “marital use” but “natural use.” He meant that which takes place with organs created so that the two sexes can unite through them for generation. Consequently, when someone unites with a prostitute using the same organs, it is natural use, yet not praiseworthy but blameworthy. This term, “natural use,” therefore did not praise marital union. It identified acts more unclean and criminal than if they had used women unlawfully but nevertheless naturally’ (Augustine, Marriage and Desire 2.20.35). That is: this intercourse with the female which the apostle called natural is not understood as marital, so as to be shown good and lawful. Rather, he says, it is called natural because it indicates that the difference of sex was instituted to prepare both for union and for birth. Since these exertions gained him nothing, why did he spend so long on them? Certainly only so that his followers might think a point answered merely because they saw it touched. A brief argument will show how he said nothing. The apostle says intercourse with the female was naturally instituted; he did not commend some different union originally ordained. Discussing the intercourse in which he knew sexual desire had flourished at every period, he called it natural.