22. Like the foregoing considerations is what I shall now say about repenting. For as among all sane people it is agreed, and this the Manichæans themselves not only confess but also teach, that to repent of sin is useful. Why shall I now, in this matter, collect the testimonies of the divine Scriptures, which p. 107 are scattered throughout their pages? It is also the voice of nature; notice of this thing has escaped no fool. We should be undone, if this were not deeply imbedded in our nature. Some one may say that he does not sin; but no barbarity will dare to say, that if one sins he should not repent of it. This being the case, I ask to which of the two kinds of souls does repenting pertain? I know indeed that it can pertain neither to him who does ill nor to him who cannot do well. Wherefore, that I may use the words of the Manichæans, if a soul of darkness repent of sin, it is not of the substance of supreme evil, if a soul of light, it is not of the substance of supreme good; that disposition of repenting which is profitable testifies alike that the penitent has done ill, and that he could have done well. How, therefore, is there from me nothing of evil, if I have acted unadvisedly, or how can I rightly repent if I have not so done? Hear the other part. How is there from me nothing of good, if in me there is good will, or how do I rightly repent if there is not? Wherefore, either let them deny that there is great utility in repenting, so that they may be driven not only from the Christian name, but from every even imaginary argument for their views, or let them cease to say and to teach that there are two kinds of souls, one of which has nothing of evil, the other nothing of good; for that whole sect is propped up by this two-headed 218 or rather headlong 219 variety of souls.
23. And to me indeed it is sufficient thus to know that the Manichæans err, that I know that sin must be repented of; and yet if now by right of friendship I should accost some one of my friends who still thinks that they are worthy of being listened to, and should say to him: Do you not know that it is useful, when any one has sinned, to repent? Without hesitation he will swear that he knows. If then I shall have convinced you that Manichæism is false, will you not desire anything more? Let him reply what more he can desire in this matter. Very well, so far. But when I shall have begun to show the sure and necessary arguments which, bound to it with adamantine chains, as the saying is, follow that proposition, and shall have conducted to its conclusion the whole process by which that sect is overthrown, he will deny perhaps that he knows the utility of repenting, which no learned man, no unlearned, is ignorant of, and will rather contend, when we hesitate and deliberate, that two souls in us furnish each its own proper help to the solution of the different parts of the question. O habit of sin! O accompanying penalty of sin! Then you turned me away from the consideration of things so manifest, but you injured me when I did not discern. But now, among my most familiar acquaintances who do not discern, you wound and torment me discerning.