We must therefore say that all these things took place miraculously by Divine power. Whence Augustine says (Sup. Joan. Tract. 121): "To the substance of a body in which was the Godhead closed doors were no obstacle. For truly He had power to enter in by doors not open, in Whose Birth His Mother's virginity remained inviolate." And Dionysius says in an epistle (Ad Caium iv) that "Christ excelled man in doing that which is proper to man: this is shown in His supernatural conception, of a virgin, and in the unstable waters bearing the weight of earthly feet." _______________________
THIRD ARTICLE [III, Q. 28, Art. 3]
Whether Christ's Mother Remained a Virgin After His Birth?
Objection 1: It would seem that Christ's Mother did not remain a virgin after His Birth. For it is written (Matt. 1:18): "Before Joseph and Mary came together, she was found with child of the Holy Ghost." Now the Evangelist would not have said this—"before they came together"—unless he were certain of their subsequent coming together; for no one says of one who does not eventually dine "before he dines" (cf. Jerome, Contra Helvid.). It seems, therefore, that the Blessed Virgin subsequently had intercourse with Joseph; and consequently that she did not remain a virgin after (Christ's) Birth.
Obj. 2: Further, in the same passage (Matt. 1:20) are related the words of the angel to Joseph: "Fear not to take unto thee Mary thy wife." But marriage is consummated by carnal intercourse. Therefore it seems that this must have at some time taken place between Mary and Joseph: and that, consequently she did not remain a virgin after (Christ's) Birth.
Obj. 3: Further, again in the same passage a little further on (Matt. 1:24, 25) we read: "And" (Joseph) "took unto him his wife; and he knew her not till she brought forth her first-born Son." Now this conjunction "till" is wont to designate a fixed time, on the completion of which that takes place which previously had not taken place. And the verb "knew" refers here to knowledge by intercourse (cf. Jerome, Contra Helvid.); just as (Gen. 4:1) it is said that "Adam knew his wife." Therefore it seems that after (Christ's) Birth, the Blessed Virgin was known by Joseph; and, consequently, that she did not remain a virgin after the Birth (of Christ).
Obj. 4: Further, "first-born" can only be said of one who has brothers afterwards: wherefore (Rom. 8:29): "Whom He foreknew, He also predestinated to be made conformable to the image of His Son; that He might be the first-born among many brethren." But the evangelist calls Christ the first-born by His Mother. Therefore she had other children after Christ. And therefore it seems that Christ's Mother did not remain a virgin after His Birth.
Obj. 5: Further, it is written (John 2:12): "After this He went down to Capharnaum, He"—that is, Christ—"and His Mother and His brethren." But brethren are those who are begotten of the same parent. Therefore it seems that the Blessed Virgin had other sons after Christ.
Obj. 6: Further, it is written (Matt. 27:55, 56): "There were there"—that is, by the cross of Christ—"many women afar off, who had followed Jesus from Galilee, ministering unto Him; among whom was Mary Magdalen, and Mary the mother of James and Joseph, and the mother of the sons of Zebedee." Now this Mary who is called "the mother of James and Joseph" seems to have been also the Mother of Christ; for it is written (John 19:25) that "there stood by the cross of Jesus, Mary His Mother." Therefore it seems that Christ's Mother did not remain a virgin after His Birth.
On the contrary, It is written (Ezech. 44:2): "This gate shall be shut, it shall not be opened, and no man shall pass through it; because the Lord the God of Israel hath entered in by it." Expounding these words, Augustine says in a sermon (De Annunt. Dom. iii): "What means this closed gate in the House of the Lord, except that Mary is to be ever inviolate? What does it mean that 'no man shall pass through it,' save that Joseph shall not know her? And what is this—'The Lord alone enters in and goeth out by it'—except that the Holy Ghost shall impregnate her, and that the Lord of angels shall be born of her? And what means this—'it shall be shut for evermore'—but that Mary is a virgin before His Birth, a virgin in His Birth, and a virgin after His Birth?"