And we see that, since the human race has increased and multiplied, this is so strictly observed even among the profane worshippers of many and false gods, that though their laws perversely allow a brother to marry his sister,181 yet custom, with a finer morality, prefers to forego this licence; and though it was quite allowable in the earliest ages of the human race to marry one's sister, it is now abhorred as a thing which no circumstances could justify. For custom has very great power either to attract or to shock human feeling. And in this matter, while it restrains concupiscence within due bounds, the man who neglects and disobeys it is justly branded as abominable. For if it is iniquitous to plough beyond our own boundaries through the greed of gain, is it not much more iniquitous to transgress the recognised boundaries of morals through sexual lust? And with regard to marriage in the next degree of consanguinity, marriage between cousins, we have observed that in our own time the customary morality has prevented this from being frequent, though the law allows it. It was not prohibited by divine law, nor as yet had human law prohibited it; nevertheless, though legitimate, people shrank from it, because it lay so close to what was illegitimate, and in marrying a cousin seemed almost to marry a sister, – for cousins are so closely related that they are called brothers and sisters,182 and are almost really so. But the ancient fathers, fearing that near relationship might gradually in the course of generations diverge, and become distant relationship, or cease to be relationship at all, religiously endeavoured to limit it by the bond of marriage before it became distant, and thus, as it were, to call it back when it was escaping them. And on this account, even when the world was full of people, though they did not choose wives from among their sisters or half-sisters, yet they preferred them to be of the same stock as themselves. But who doubts that the modern prohibition of the marriage even of cousins is the more seemly regulation, – not merely on account of the reason we have been urging, the multiplying of relationships, so that one person might not absorb two, which might be distributed to two persons, and so increase the number of people bound together as a family, but also because there is in human nature I know not what natural and praiseworthy shamefacedness which restrains us from desiring that connection which, though for propagation, is yet lustful, and which even conjugal modesty blushes over, with any one to whom consanguinity bids us render respect?
The sexual intercourse of man and woman, then, is in the case of mortals a kind of seed-bed of the city; but while the earthly city needs for its population only generation, the heavenly needs also regeneration to rid it of the taint of generation. Whether before the deluge there was any bodily or visible sign of regeneration, such as was afterwards enjoined upon Abraham when he was circumcised, or what kind of sign it was, the sacred history does not inform us. But it does inform us that even these earliest of mankind sacrificed to God, as appeared also in the case of the two first brothers; Noah, too, is said to have offered sacrifices to God when he had come forth from the ark after the deluge. And concerning this subject we have already said in the foregoing books that the devils arrogate to themselves divinity, and require sacrifice that they may be esteemed gods, and delight in these honours on no other account than this, because they know that true sacrifice is due to the true God.
Since, then, Adam was the father of both lines, – the father, that is to say, both of the line which belonged to the earthly, and of that which belonged to the heavenly city, – when Abel was slain, and by his death exhibited a marvellous mystery, there were henceforth two lines proceeding from two fathers, Cain and Seth, and in those sons of theirs, whom it behoved to register, the tokens of these two cities began to appear more distinctly. For Cain begat Enoch, in whose name he built a city, an earthly one, which was not from home in this world, but rested satisfied with its temporal peace and happiness. Cain, too, means "possession;" wherefore at his birth either his father or mother said, "I have gotten a man through God." Then Enoch means "dedication;" for the earthly city is dedicated in this world in which it is built, for in this world it finds the end towards which it aims and aspires. Further, Seth signifies "resurrection," and Enos his son signifies "man," not as Adam, which also signifies man but is used in Hebrew indifferently for man and woman, as it is written, "Male and female created He them, and blessed them, and called their name Adam,"183 leaving no room to doubt that though the woman was distinctively called Eve, yet the name Adam, meaning man, was common to both. But Enos means man in so restricted a sense, that Hebrew linguists tell us it cannot be applied to woman: it is the equivalent of the "child of the resurrection," when they neither marry nor are given in marriage.184 For there shall be no generation in that place to which regeneration shall have brought us. Wherefore I think it not immaterial to observe that in those generations which are propagated from him who is called Seth, although daughters as well as sons are said to have been begotten, no woman is expressly registered by name; but in those which sprang from Cain at the very termination to which the line runs, the last person named as begotten is a woman. For we read, "Methusael begat Lamech. And Lamech took unto him two wives: the name of the one was Adah, and the name of the other Zillah. And Adah bare Jabal: he was the father of the shepherds that dwell in tents. And his brother's name was Jubal: he was the father of all such as handle the harp and organ. And Zillah, she also bare Tubal-Cain, an instructor of every artificer in brass and iron: and the sister of Tubal-Cain was Naamah."185 Here terminate all the generations of Cain, being eight in number, including Adam, – to wit, seven from Adam to Lamech, who married two wives, and whose children, among whom a woman also is named, form the eighth generation. Whereby it is elegantly signified that the earthly city shall to its termination have carnal generations proceeding from the intercourse of males and females. And therefore the wives themselves of the man who is the last named father of Cain's line are registered in their own names, – a practice nowhere followed before the deluge save in Eve's case. Now as Cain, signifying possession, the founder of the earthly city, and his son Enoch, meaning dedication, in whose name it was founded, indicate that this city is earthly both in its beginning and in its end, – a city in which nothing more is hoped for than can be seen in this world, – so Seth, meaning resurrection, and being the father of generations registered apart from the others, we must consider what this sacred history says of his son.
"And to Seth," it is said, "there was born a son, and he called his name Enos: he hoped to call on the name of the Lord God."186 Here we have a loud testimony to the truth. Man, then, the son of the resurrection, lives in hope: he lives in hope as long as the city of God, which is begotten by faith in the resurrection, sojourns in this world. For in these two men, Abel, signifying "grief," and his brother Seth, signifying "resurrection," the death of Christ and His life from the dead are prefigured. And by faith in these is begotten in this world the city of God, that is to say, the man who has hoped to call on the name of the Lord. "For by hope," says the apostle, "we are saved: but hope that is seen is not hope: for what a man seeth, why doth he yet hope for? But if we hope for that we see not, then do we with patience wait for it."