Origen of Alexandria : "And her days were fulfilled," it says, "that she should bring forth, and there were twins in her belly." This saying, that is, "her days were fulfilled that she should bring forth," is almost never written except of holy women. For this was said of this Rebekah, and of Elizabeth the mother of John, and of Mary the mother of our Lord Jesus Christ. Whence it seems to me that a childbirth of this kind shows forth something excellent and beyond other human beings, and that the fullness of days indicates the birth of a perfect offspring. — HOMILIES ON Genesis 12.3