The books On the City of God, which you most eagerly demanded of me, I have now sent to you, re-read even by myself as I had promised. That this might be done — with God's help indeed — my son, your own brother Cyprian, truly pressed me exactly as I wished to be pressed. There are twenty-two quires, which to reduce into a single volume would be a great labor. And if you wish two codices to be made, they must be so divided that one has ten books, the other twelve. For in those ten the vanities of the impious are refuted, while in the remaining ones our religion is set forth and defended — although in the former this too was done where it was more fitting, and in the latter that also.
But if you prefer the volumes to be more than two, then you should make five codices, of which the first would contain the first five books, in which the argument is against those who contend that the worship — not indeed of gods but of demons — is profitable for the felicity of this life; the second, the next five, which hold that gods, whether such as these or however many of any kind, are to be worshipped through sacred rites and sacrifices for the sake of the life that is to come after death. Then the three remaining codices that follow will need to have four books each. For this same portion has been so distributed by us that four should display the rise of that City, an equal number its progress — or, as we preferred to say, its course — and the last four its due ends.
If you shall be as diligent in reading these books as you were in obtaining them, you will learn by your own experience, rather than by my promise, how much they help. But since our brethren there at Carthage do not yet have those parts pertaining to this work which is On the City of God, I ask that you graciously and gladly grant them, when they request it, leave to make copies. For you will give to no great number, but scarcely to one or two, and they in turn will give to the rest. As for your friends — whether within the Christian people they desire to be instructed, or are held by some superstition from which they may seem able, through this labor of ours, to be freed by the grace of God — you yourself will see how to share it. For my part, if the Lord wills, I shall by my writings frequently take care to inquire how far you have advanced in reading.
It does not escape you, as a learned man, how much repeated reading helps toward understanding what is read. For where there is ease of reading, the difficulty of understanding is either none or certainly very slight, and that ease grows the more it is repeated, so that by assiduity what through negligence had been unripe may ripen. Most excellent lord, deservedly honorable and to be cherished, my son Firmus: concerning those books which I wrote On the Academics at the time of my recent conversion — since you showed in your earlier letter to me that they had come to your excellency's notice — I beg you to write back how you obtained them. And how much the composition of the twenty-two books amounts to, the little summary I have sent will indicate.