Genesis 4:17

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.

And Cain knew his wife. Her name is traditionally said to have been Save; and as it was an uninhabited region in which Cain sought refuge, it follows that she must have accompanied him in his flight. No previous mention is made of Cain's marriage; but that is not wonderful in so succinct and fragmentary a history: and whether she was a daughter of Adam or of one of his numerous sons, no objection can be made against the propriety of such a connection, as marriages with near relatives were matters of necessity in the infancy of the human race.

Moveover, the law of incest was not promulgated until long after (Leviticus 18:9), nor was there any necessity for such an enactment, as no practical evils could result from the formation of such unions, when mankind was not yet developed into separate families.

And she ... bare Enoch - i:e., initiating-a suitable name for a first-born son.

And he builded a city. Some, deriving the Hebrew word "city" from a root signifying to be deep, maintain that it was a cave, in which Cain established himself, and thus he was the first Troglodyte. But such an idea is inconsistent with the language of the context, which expressly relates that he "builded (built)" or "began to build"; and whether the habitations erected consisted of huts made of boughs, plastered with clay and thatched with grass, like those in many modern towns of Arabia; whether they were wholly mud cabins, which in early times were (Job 4:19; Job 24:16), and still are so common in the East; or whether they were formed of huge blocks of stone, like the rocky fastnesses of the Rephaim, that have been discovered in such vast numbers in Bashan, they would doubtless be rude and simple structures. Nor must we in our thoughts assimilate this primeval city to the gigantic scale on which towns were extended in later times.

Whether it covered a large or small area, it was fortified, as the original word signifies, by a wall of mud or unconnected stones, or by a fence of cactus-like the briars or prickly pears that defend the modern Jericho, and many other villages of Palestine in the present day. It was a new stage in the development of human society, because it formed the commencement of a settled mode of life; and although many of its inhabitants, like those in ancient Canaan, might continue their agricultural pursuits by tilling small patches of land in the outskirts (cf. Judges and Ruth), yet it gradually led to the formation of different habits, and by the necessities felt and the requirements created, it whetted invention, stimulated industry, and gave a strong impulse to the culture of the useful no less than the fine arts. Although the erection of this city is recorded apparently in the continuous course of events subsequent to Cain's exile, and immediately after the birth of his oldest son, it is probable that centuries had elapsed, and he himself, as Augustine suggests, was an old man, some 500 or 600 years of age, when he laid its foundations.

It was ominous of its future character, that, like Rome in later ages, it was associated with the murder of the founder's brother. Its grand radical defect was its irreligious origin; it was "of the earth, earthy;" and although it is not expressly said that its builder, like those of Babel, aimed at making to himself a name, that he and his might not be scattered abroad upon the face of the earth, yet its inhabitants naturally imitated their ancestor, and in its increasing population a society was formed, of which ungodliness, luxury, and voluptuousness were the characteristic features. Even if we do not regard this city as 'the first foundation-stone of the kingdom of the world, in which the spirit of the beast bears sway,' we cannot doubt the prevailing irreligion of the place.