City of God

Therefore that God, the author and giver of felicity, because He alone is the true God, Himself gives earthly kingdoms both to good and bad. Neither does He do this rashly, and, as it were, fortuitously,— because He is God not fortune—but according to the order of things and times, which is hidden from us, but thoroughly known to Himself; which same order of times, however, He does not serve as subject to it, but Himself rules as lord and appoints as governor. Felicity He gives only to the good.

Whether a man be a subject or a king makes no difference; he may equally either possess or not possess it. And it shall be full in that life where kings and subjects exist no longer. And therefore earthly kingdoms are given by Him both to the good and the bad; lest His worshippers, still under the conduct of a very weak mind, should covet these gifts from Him as some great things. And this is the mystery of the Old Testament, in which the New was hidden, that there even earthly gifts are promised: those who were spiritual understanding even then, although not yet openly declaring, both the eternity which was symbolized by these earthly things, and in what gifts of God true felicity could be found.