Genesis 4:17

Of these two first parents of the human race, then, Cain was the first-born, and he belonged to the city of men; after him was born Abel, who belonged to the city of God. For as in the individual the truth of the apostle’s statement is discerned, “that is not first which is spiritual, but that which is natural, and afterward that which is spiritual,” whence it comes to pass that each man, being derived from a condemned stock, is first of all born of Adam evil and carnal, and becomes good and spiritual only afterwards, when he is grafted into Christ by regeneration: so was it in the human race as a whole. …

Therefore, although it is written, “And Cain knew his wife, and she conceived and bare Enoch, and he builded a city and called the name of the city after the name of his son Enoch,” it does not follow that we are to believe this to have been his first-born; for we cannot suppose that this is proved by the expression “he knew his wife,” as if then for the first time he had had intercourse with her. For in the case of Adam, the father of all, this expression is used not only when Cain, who seems to have been his first-born, was conceived, but also afterwards the same Scripture says, “Adam knew Eve his wife, and she conceived, and bare a son, and called his name Seth.” Whence it is obvious that Scripture employs this expression neither always when a birth is recorded nor then only when the birth of a first-born is mentioned. …

18. “And there shall be a firmament on the earth, on the tops of the mountains” ( ver. 16 ). For, “all the promises of God in Him are Yea,” that is, in Him are confirmed: because in Him hath been fulfilled whatever hath been prophesied for our salvation. For the tops of the mountains it is meet to understand as the authors of the divine Scriptures, that is, those persons through whom they were supplied: wherein He is indeed Himself the Firmament: for unto Him all things that have been divinely written are ascribed. But this He willed should be on earth; because for the sake of those that are upon earth, they were written. Whence He came also Himself upon earth, in order that He might confirm all these things, that is, in Himself might show them to have been fulfilled. …

7. Evidently this description cannot be taken literally (in fact, it is absurd to suppose a city the length, breadth and height of which are all twelve thousand furlongs), and therefore the details of it must be mystically understood. The great city which Cain first built and called after his son must be taken to represent this world, which the devil, that accuser of his brethren, that fratricide who is doomed to perish, has built of vice cemented with crime, and filled with iniquity. Therefore it is spiritually called Sodom and Egypt. Thus it is written, “Sodom shall return to her former estate,” that is to say, the world must be restored as it has been before. For we cannot believe that Sodom and Gomorrah, Admah and Zeboim are to be built again: they must be left to lie in ashes forever. We never read of Egypt as put for Jerusalem: it always stands for this world. …

Serenus : You have propounded two not unimportant questions, to which I will reply, to the best of my ability, in the order in which you have raised them. We cannot possibly believe that spiritual existences can have carnal intercourse with women. But if this could ever have literally happened how is it that it does not now also sometimes take place, and that we do not see some in the same way born of women by the agency of demons without intercourse with men? especially when it is clear that they delight in the pollution of lust, which they would certainly prefer to bring about through their own agency rather than through that of men, if they could possibly manage it, as Ecclesiastes declares: “What is it that hath been? The same that is. And what is it that hath been done? The same that is done. …