Genesis 16:2

That I may obtain children by her. — Heb., that I may be builded by her. The words, ben=a son, bath (originally banth)=a daughter, baith (banith) =a house, and bânâh=to build, all belong to the same root in Hebrew, the idea being that the children build the house, and give a man the pledge of continuance. Until late times the tent was the habitation, while the house was the family (Genesis 7:1). Thus the phrase “to build a man a sure house” meant, to give him lasting prosperity (1 Samuel 2:35). Hence, too, the close connection between building and the bestowal of children in Psalms 127. As then the children of a woman bestowed by her mistress upon the husband were regarded as belonging to the wife (Genesis 30:3), Sarah, despairing of bearing a son herself, as she was now seventy-five, and had been ten years in Canaan, concluded that her heir was to be born of a substitute.

As regards the morality of the act, we find that marriage with one wife was the original law (Genesis 2:24), and that when polygamy was introduced it was coupled by the inspired narrator with violence and licence (Genesis 4:19). Monogamy was the rule, as we see in the households of Noah, Terah, Isaac, and others; but many, like Esau and Jacob, allowed themselves a greater latitude. In so doing, their conduct falls below the level of Christian morality, but everyone’s actions are strongly influenced by the general views of the people among whom he lives; and in Abram’s case it must be said in his defence that, with so much depending on his having offspring, he took no steps to obtain another wife, but remained content with the barren Sarai. When he did take Hagar it was at his wife’s request, and for a reason which seemed to them adequate, and even religious. Rachel subsequently did the same for a much lower motive. The consent of the wife was in such cases all-important; and so in India, in ancient times, it was necessary to make a second marriage valid (see Wilson’s Hindu Theatre, i. 179).