New Defender's Study Bible Notes
4:17 knew his wife. His wife was probably one of Adam’s daughters (see Genesis 5:4), although it could have been a later descendant, since it would easily have been possible for the population to grow to several hundred thousand by the time of Cain’s death.
4:17 Enoch. Cain named his son “Enoch,” meaning “dedication” or “commencement,” probably signifying the beginning of a new manner of life.
4:17 city. Urbanization is usually considered by evolutionary archaeologists to be one of the first indicators of the emergence of true civilization from a hunting-and-gathering culture (so-called stone age culture). It is significant that true civilized cultures, by this definition, have existed since the very first generation following Adam, with no suggestion whatever of a long evolutionary advance from an imaginary stone age. Evidently Cain, unable to survive either as a farmer or by trade, had to develop his own self-sufficient economy, through the patriarchal clan which he established around his son Enoch and the city which Cain built for him.