Some one, then, will say, Is it to be believed that a man who intended to beget children, and had no intention of continence, abstained from sexual intercourse a hundred years and more, or even, according to the Hebrew version, only a little less, say eighty, seventy, or sixty years; or, if he did not abstain, was unable to beget offspring? This question admits of two solutions. For either puberty was so much later as the whole life was longer, or, which seems to me more likely, it is not the first-born sons that are here mentioned, but those whose names were required to fill up the series until Noah was reached, from whom again we see that the succession is continued to Abraham, and after him down to that point of time until which it was needful to mark by pedigree the course of the most glorious city, which sojourns as a stranger in this world, and seeks the heavenly country. That which is undeniable is that Cain was the first who was born of man and woman. For had he not been the first who was added by birth to the two unborn persons, Adam could not have said what he is recorded to have said, "I have gotten a man by the Lord."[176] He was followed by Abel, whom the elder brother slew, and who was the first to show, by a kind of foreshadowing of the sojourning city of God, what iniquitous persecutions that city would suffer at the hands of wicked and, as it were, earth-born men, who love their earthly origin, and delight in the earthly happiness of the earthly city. But how old Adam was when he begat these sons does not appear. After this the generations diverge, the one branch deriving from Cain, the other from him whom Adam begot in the room of Abel slain by his brother, and whom he called Seth, saying, as it is written, "For God hath raised me up another seed for Abel whom Cain slew."[177] These two series of generations accordingly, the one of Cain, the other of Seth, represent the two cities in their distinctive ranks, the one the heavenly city, which sojourns on earth, the other the earthly, which gapes after earthly joys, and grovels in them as if they were the only joys. But though eight generations, including Adam, are registered before the flood, no man of Cain's line has his age recorded at which the son who succeeded him was begotten. For the Spirit of God refused to mark the times before the flood in the generations of the earthly city, but preferred to do so in the heavenly line, as if it were more worthy of being remembered. Further, when Seth was born, the age of his father is mentioned; but already he had begotten other sons, and who will presume to say that Cain and Abel were the only ones previously begotten? For it does not follow that they alone had been begotten of Adam, because they alone were named in order to continue the series of generations which it was desirable to mention. For though the names of all the rest are buried in silence, yet it is said that