To Florus 5.30

These points no longer slip from our grasp, but the Manichaean and the advocate of inherited sin reject them with equal determination. Let us see, then, what they themselves say. Mani writes that sin is natural. Augustine agrees that sin is natural. Both therefore dissent from the definition we gave, and form an association in calling sin natural. Let us also see what they say about the kind of sin—what they regard as the sin both affirm to be natural—lest perhaps they disagree at the next step. What does Mani write to his daughter? That fleshly desire, and the pleasure appointed for the work of fertility, is proved diabolical because its act avoids public view. What does Augustine say? Exactly the same: ‘That fleshly desire is the devil’s shrub, the cause and law of sin, which everywhere avoids observation and seeks privacy through shame’ (Augustine, Marriage and Desire 1.7.8; 1.23.26). Thus they differ neither in their first nor their second account of evil.

What is the third point? When asked where evil comes from, Mani says, ‘From the eternal nature of darkness.’ What does Augustine say? ‘My teacher goes too far in thinking evil never began. It began through the first man’s will—or rather, already through the will of a higher nature, the angelic—but from that time it became natural.’ His teacher naturally beats him and drags him to court with great authority. How will a catholic judge between them? Mani is undoubtedly exceedingly foolish in thinking sin natural; but compared with Augustine’s intelligence, he looks very acute. They agree that sin is natural, confess that this sin is of one kind, and think it possesses the entire human race. Yet afterward the pupil dares to say that in one person alone it was not natural, although he confesses it innate in everyone else! After disgracing him with a schoolboy’s beating, they will place him under his teacher, whose blasphemy is more consistent. But they will expel both pupil and teacher together from the assembly of the devout. See, then, what we allow you. You dislike Mani’s statement that evil is natural. Say, then, that no one is born guilty, and you have escaped—by denying original sin, of course. But you do not say this. You therefore confess that you wish neither to leave your teacher nor to join the catholics.