a rock, is expressive of mount Sinai in Arabia, and answereth to the present Jerusalem, which is in bondage with her children.

For it is written, Rejoice thou barren, that for a while didst not bear, break forth and cry aloud for joy, thou that didst not travail with child; for many more are the children of the desolate than of her that hath an husband."

But what saith the scripture? "Cast out the servant and her son: for the son of the servant shall not inherit with the son of the free-woman."