There it is written that Abraham had two sons, one by the slave girl, the other by his freeborn wife. The son of the slave girl had been begotten in the course of nature, but the son of the free woman was the fruit of the promise. All this is an allegory: the two women stand for two covenants. One is from Mount Sinai, and brought forth children to slavery; this is Hagar. The mountain Sinai is in Arabia and corresponds to the Jerusalem of our time, which is likewise in slavery with her children. But the Jerusalem on high is freedom, and it is she who is our mother. That is why Scripture says:
"Rejoice, you barren one who bear no children;You, my brothers, are children of the promise, as Isaac was. But just as in those days the son born in nature's course persecuted the one whose birth was in the realm of spirit, so do we find it now. What does Scripture say on the point? "Cast out slave girl and son together; for the slave girl's son shall never be an heir on equal terms with the son" of the one born free.
break into song, you stranger to the pains of childbirth!
For many are the children of the wife deserted—
far more than of her who has a husband!"
Therefore, my brothers, we are not children of a slave girl but of a motherr who is free.