St. John Chrysostom (Homily on the Gospel of Matthew, 5.3)
And when Joseph had taken her, "he had no relations with her until she had borne a son." Matthew has here used the word until not that you should suspect that afterward Joseph did know her but to inform you that before the birth the Virgin was wholly untouched by man. But why, then, it may be said, has he used the word until? Because it is common in Scripture that this expression is used without reference to specific, limited times. Here are three examples. First, in the narrative of the ark it was said that "the raven did not return until the earth was dried up," (Gen. 8:7), yet the raven did not return even after that limited time. Second, when discussing God the Scripture says, "You are from everlasting to everlasting," (Ps. 90:2), but there is no implication here that some limite is being fixed -- rather the opposite. Third, when preaching the gospel beforehand and saying, "In his days may righteousness flourish, and peace abound, until the moon be no more!" (Ps. 72:7) it is not thereby setting a temporal limit to this beautiful part of creation. So then here likewise, it uses the word until to make certain what was before the birth, but as to what follows, it leaves some further inference to be made. So it is necessary to learn what Matthew teaches: that the Virgin was untouched by man until the birth. But the rest is left for you to perceive, both as a consequence of the previous narrative and what was later acknowledged: that not even after having become a mother and having been counted worthy of a new sort of travail and a childbearing so strange, could that righteous man ever have permitted himself to have sexual relations with her.
From Ancient Christian Commentary on Scripture, New Testament, Ia, pp. 19-20, InterVarsity Press, Downers, Grove, IL.
Chromatius (friend of St. Jerome), Tractate on Matthew, 3.1
But concerning what the Evangelist said, "And he did not know her till she had borne her firstborn son," not a few careless people insist on asking whether after the Lord\'s birth the holy mother Mary had relations with Joseph. But this is not admissible on the grounds of either faith or truth. Far be it indeed that after the sacrament of so great a mystery and after the birth of the sublime Lord, one should believe that the Virgin Mary was intimate with a man. Remember that Miriam the prophetess of the Old Testament (the sister of Moses and Aaron) remained a virgin unsullied by man, having beheld the light of heavenly signs after the plagues of Egypt and the parting of the Red Sea and the Lord\'s glory going in advance and seen in the pillar of fire and clouds. It is not plausible therefore that the Mary of the Gospel, a virgin bearing God, who beheld God\'s glory not in a cloud but was worthy of carrying him in her virginal womb, had relations with a man. Noah, who was made worthy to converse with God, declared that he would abstain from the conjugal need. Moses, after hearing God calling him from the bush, abstained from conjugal relations. Now are we to believe that Joseph, the man who always did what was right, had relations with holy Mary after the birth of the Lord?
From Ancient Christian Commentary on Scripture, New Testament, Ia, p. 19, InterVarsity Press, Downers, Grove, IL.
