For it is written that Abraham had two sons, one by the slave woman and the other by the freeborn woman. The son of the slave woman was born naturally, the son of the freeborn through a promise. Now this is an allegory. These women represent two covenants. One was from Mount Sinai, bearing children for slavery; this is Hagar. Hagar represents Sinai, a mountain in Arabia; it corresponds to the present Jerusalem, for she is in slavery along with her children. But the Jerusalem above is freeborn, and she is our mother.