I Promised to write of the rise, progress, and appointed end of the two cities, one of which is God's, the other this world's, in which, so far as mankind is concerned, the former is now a stranger. But first of all I undertook, so far as His grace should enable me, to refute the enemies of the city of God, who prefer their gods to Christ its founder, and fiercely hate Christians with the most deadly malice. And this I have done in the first ten books. Then, as regards my threefold promise which I have just mentioned, I have treated distinctly, in the four books which follow the tenth, of the rise of both cities. After that, I have proceeded from the first man down to the flood in one book, which is the fifteenth of this work; and from that again down to Abraham our work has followed both in chronological order. From the patriarch Abraham down to the time of the Israelite kings, at which we close our sixteenth book, and thence down to the advent of Christ Himself in the flesh, to which period the seventeenth book reaches, the city of God appears from my way of writing to have run its course alone; whereas it did not run its course alone in this age, for both cities, in their course amid mankind, certainly experienced chequered times together just as from the beginning. But I did this in order that, first of all, from the time when the promises of God began to be more clear, down to the virgin birth of Him in whom those things promised from the first were to be fulfilled, the course of that city which is God's might be made more distinctly apparent, without interpolation of foreign matter from the history of the other city, although down to the revelation of the new covenant it ran its course, not in light, but in shadow. Now, therefore, I think fit to do what I passed by, and show, so far as seems necessary, how that other city ran its course from the times of Abraham, so that attentive readers may compare the two.