"For these women", he says, "are two covenants; one from Mount Sinai, bearing...

[Anonymous]

"For these women", he says, "are two covenants; one from Mount Sinai, bearing children unto bondage, which is Hagar".
These: who? The mothers of those children, Sarah and Hagar; and what are they? Two Covenants, two Laws. As the names of the women were given in the history, he abides by this designation of the two races, showing how much follows from the very names. How from the names?

"Now this Hagar is Mount Sinai in Arabia":
The bond-woman was called Hagar, and Hagar is the word for Mount Sinai in the language of that country. So that it is necessary that all who are born of the Old Covenant should be bondmen, for that mountain where the Old Covenant was delivered has a name in common with the bondwoman. And it includes Jerusalem, for this is the meaning of, "And answers to Jerusalem that now is."
That is, it borders on, and is contiguous to it.

"For she is in bondage with her children."
What follows from hence? Not only that she was in bondage and brought forth bondmen, but that this Covenant is so too, whereof the bondwoman was a type. For Jerusalem is adjacent to the mountain of the same name with the bondwoman, and in this mountain the Covenant was delivered. Now where is the type of Sarah?

"But Jerusalem that is Above is free."
Those therefore, who are born of her are not bondmen. Thus the type of the Jerusalem below was Hagar, as is plain from the mountain being so called; but of that which is above is the Church. Nevertheless he is not content with these types, but adds the testimony of Isaiah to what he has spoken. Having said that Jerusalem which is Above is our Mother, and having given that name to the Church, he cites the suffrage of the Prophet in his favor, "Rejoice, thou barren that bearest not, break forth and cry, thou that travailest not, for more are the children of the desolate than of her which has the husband. (Isaiah 54:1)

Who is this who before was barren, and desolate? Clearly it is the Church of the Gentiles, that was before deprived of the knowledge of God? Who, she which has the husband? plainly the Synagogue. Yet the barren woman surpassed her in the number of her children, for the other embraces one nation, but the children of the Church have filled the country of the Greeks and of the Barbarians, the earth and sea, the whole habitable world. Observe how Sarah by acts, and the Prophet by words, have described the events about to befal us. Observe too, that he whom Isaiah called barren, Paul has proved to have many children, which also happened typically in the case of Sarah. For she too, although barren, became the mother of a numerous progeny. This however does not suffice Paul, but he carefully follows out the mode whereby the barren woman became a mother, that in this particular likewise the type might harmonize with the Truth.

- St. John Chrysostom, Homily On Galatians 4:24-27.