And he knew her not till she brought forth her firstborn son: and he called his name JESUS.

“(Cont. Helvid. c. 5.) Helvidius is at much superfluous trouble to make this word know refer to carnal knowledge rather than to acquaintance, as though any had ever denied that; or as if the follies to which he replies had ever occurred to any person of common understanding. He then goes on to say, that the adverb ‘until’ denotes a fixed time when that should take place, which had not taken place before; so that here from the words, He knew her not until she had brought forth her first-born Son, it is clear, he says, that after that he did know her. And in proof of this he heaps together many instances from Scripture. To all this we answer, that the word ‘until’ is to be understood in two senses in Scripture. And concerning the expression, knew her not, he has himself shewn, that it must be referred to carnal knowledge, none doubting that it is often used of acquaintance, as in that, The child Jesus tarried behind in Jerusalem, and His parents knew not of it. (Luke 2:43.) In like manner ‘until’ often denotes in Scripture, as he has shewn, a fixed period, but often also an infinite time, as in that, Even to your old age I am He. (Isa. 46:4.) Will God then cease to be when they are grown old? Also the Saviour in the Gospel, Lo, I am with you always, even to the end of this world. (Mat. 28:20.) Will He then leave His disciples at the end of the world? Again, the Apostle says, He must reign till He has put His enemies under His feel. (1 Cor. 15:25.) Be it understood then, that that which if it had not been written might have been doubted of, is expressly declared to us; other things are left to our own understandingc. So here the Evangelist informs us, in that wherein there might have been room for error, that she was not known by her husband until the birth of her Son, that we might thence infer that much less was she known afterwards.”

“Above, the Evangelist proved that the Mother of God conceived of the Holy Spirit from two things, namely from the revelation of the Angel and from the foretelling of the prophet; he intends to show this same thing from the obedience of Joseph, who would not have acquiesced to the words of the Angel so as to take Mary as his spouse, unless he had known her to be pregnant by the Holy Spirit. And concerning this he does two things: first, the obedience of the spouse himself to the Angel is set forth; second, the manner of the obedience is described, there at "and he took." And note that because through the disobedience of the first man we fell into sin — Romans 5:19: "through the disobedience of one man many were made sinners" — therefore at the beginning of our reparation obedience is set forth. And we can note four things which are necessary for obedience. The first is that it be ordered. And I say ordered, because first vices must be abandoned, and afterward one must obey unto the operation of the virtues; Jeremiah 4:3: "Break up your fallow ground, and sow not upon thorns," and so forth. And therefore here it is said that Joseph, rising up from sleep — namely, from the sleep of sloth and of doubt. Concerning this sleep it is said, Ephesians 5:14: "Rise, you who sleep, and arise from the dead." The second, indeed, is that it must be prompt: and this is what is said, Ecclesiasticus 5:8: "Delay not from day to day, be not slow to turn to the Lord; for his wrath will come suddenly." And therefore here it is said that he immediately did as he commanded him. The Gloss: whoever is admonished by God should dissolve delays, rise from sleep, and do what is commanded. The third, indeed, is that it must be perfect, so that not only what is commanded is done, but it is done in the manner in which it is commanded and in the way in which it is enjoined upon them. Hence here it is said "as he had commanded." The Gloss: perfect obedience. Colossians 3:20: "Children, obey your parents in all things." The fourth is that it must be discreet, so that obedience is given to him to whom it is owed, and in that in which it is owed, so that nothing is done against God: hence it says that he did as the Angel commanded him — not an evil spirit, but one of God. 1 John 4:1: "Do not believe every spirit, but test the spirits, whether they be of God, because many false prophets have gone out into the world," and so forth. "And he took." Here it is shown in what things he obeyed, and three things are set forth: first, the obedience which he showed to the Angel; second, the reverence which he showed to the mother; third, the compliance which he showed to Christ once born. The Angel commanded Joseph: "Do not fear to take Mary as your wife." And Joseph did as he commanded, and so forth. Whence it is clear that he found the woman good. But did he not already have her in the house? Why then does it say, rising up... he took? Chrysostom answers: because he had not cast her out from the house, but from his heart. Or because she was first taken in betrothal, but the nuptials were still to be celebrated afterward, and then it is said that she is taken, and that she is a wife. And lest anyone should suspect that carnal union intervened, he adds, "and he did not know her." Here it must be known that this word "to know" is taken in two ways in Sacred Scripture: sometimes for recognition, John 14:7: "and henceforth you shall know him, and you have seen him"; sometimes for carnal union, as in Genesis 4:1: "And Adam knew his wife Eve," etc., namely, carnally. But an objection is raised, because it is not said simply that he did not know her, etc., but "until she brought forth her son." Therefore afterward he knew her; whence also Helvidius said that although as a virgin she conceived Christ, nevertheless afterward she had other sons by Joseph. And therefore Jerome says that "until" sometimes signifies something finite and determinate, as if I should say, "I will not come until I eat," because thereby I signify that I am going to come afterward; but sometimes it signifies infinitely and indeterminately, for example 1 Corinthians 15:25: "For he must reign, until he puts all his enemies under his feet." Will he then not reign afterward? Indeed he will; but Scripture uses such a manner of speaking because it intends to remove that which could be doubtful. For it could be doubtful whether he would reign, at a time when he had not yet put his enemies under his feet. Likewise it could be doubtful, once the Blessed Virgin had given birth, whether before the birth she had been known by Joseph — since the first point ought to come into doubt for no one, seeing that the Angels sang: "Glory to God in the highest, and on earth peace to men of good will," Luke 2:14. And this, therefore, is what the Evangelist intends. And Jerome argues excellently against Helvidius: "You say, Helvidius, that before this Joseph did not know her, because he had been admonished in his sleep by the Angel. If, then, an admonition in sleep so availed that he did not join himself to Mary, how much more the knowledge of the Angels, the adoration of the shepherds and of the magi?" Chrysostom, however, took "knowledge" for intellectual recognition: that is, he did not know how great her dignity was; but after she gave birth, he came to know it. Others say that it is taken for sensible recognition, and thus the opinion of these is fairly probable as well. For they say that Moses, from the Lord's speaking with him, had such brightness in his face that the children of Israel could not gaze intently upon his face, 2 Corinthians 3:7. Therefore if Moses had this from his fellowship with God, much more did this Blessed Virgin, who bore him in her womb, have such brightness in her face that Joseph did not recognize her. But the first exposition is more literal. Likewise Helvidius says that the letter states, "until she brought forth her firstborn son." "First" is said with respect to a later one. Therefore she had other children. Jerome answers that it is customary in Sacred Scripture that those are called firstborn whom no others precede: Exodus 13:12 it is said that the firstborn of the Jews were to be offered to the Lord. Jerome asks: was it then necessary to wait, so that they would not be offered until a second one was born? Therefore those are called firstborn whom no others precede; and thus it is to be understood here. The compliance follows. Luke 2:21 carries this out more fully, but Matthew touches on it briefly. For thus the Holy Spirit wills, that what one has said, the other should pass over in silence. "He called his name Jesus"; this name indeed was not a little renowned among the ancients, and desired; Genesis 49:18: "I will look for your salvation, O Lord." And Habakkuk 3:18: "But I will rejoice in the Lord, and I will exult in God my Jesus."”

“And knew her not,.... Or "but he knew her not", answering to the Hebrew that is, had carnal knowledge of her, or copulation with her, though his wife. The words are an euphemism, or a modest way of expressing the conjugal act, and is a very ancient one, see Gen 4:1 and what has been used in nations and languages. And this conduct of his was necessary, till she had brought forth her firstborn; that it might be manifest not only that she conceived, being a virgin, but also that she brought forth, being a virgin: for both are signified in the prophecy before related, "a virgin shall conceive and bring forth a son"; which is all one as if it had been said, a virgin shall conceive, and "a virgin" shall bring forth a son. The "firstborn" is that which first opens the womb of its mother, whether any follows after or not, Exo 13:12. Christ is called Mary's firstborn, because she had none before him, whether she had any after him or not; for her perpetual virginity seems to be no necessary article of faith: for when it is said, Joseph knew her not till she had brought forth, the meaning is certain that he knew her not before. But whether he afterwards did or not, is not so manifest, nor is it a matter of any great importance; the word "until" may be so understood as referring to the time preceding, that the contrary cannot be affirmed of the time following, Sa2 6:23 and which may be the case here, and is indeed generally understood so; and it also may be considered as only expressive of the intermediate time, as in Mat 5:26 as Beza observes. Christ was "her firstborn" as he was man, and the firstborn of God, or his first and only begotten, as the Son of God. It is further observed, that she "called his name Jesus", as was foretold to her, or ordered her by the Angel, Luk 1:31 and to Joseph, Mat 1:21. Next: Matthew Chapter 2”

“See note on ver. 18. — St. Jerome assures us, that St. Joseph always preserved his virginal chastity. It is “ of faith ” that nothing contrary thereto ever took place with his chaste spouse, the blessed Virgin Mary. St. Joseph was given her by heaven to be the protector of her chastity, to secure her from calumnies in the birth of the Son of God, to assist her in her flight into Egypt, &c. &c. We cannot sufficiently admire the modest reserve of both parties. Mary does not venture to explain to her troubled husband the mystery of her pregnancy; and Joseph is afraid of mentioning his uneasiness and doubts, for fear of troubling her delicate mind and wounding her exquisite feelings. So great modesty, reserve and silence, are sure to be approved by heaven; and God sends an angel to Joseph in his sleep, to dissipate his doubts, and to expound to him the mystery of the incarnation. (Haydock)”

“This does not suppose that others were born afterwards. The law prescribed offerings to be made for first-born males forty days after their birth, when it could not be known whether other children would be born to the same parents. Scott says, " Observe, Christ was the First-Bo7'n, and so He might be called, although His mother had not any children after Him, according to Scripture language." Pract. Obser.”

“And knew her not till she had brought forth her first-born son: and he called his name JESUS--The word "till" does not necessarily imply that they lived on a different footing afterwards (as will be evident from the use of the same word in Sa1 15:35; Sa2 6:23; Mat 12:20); nor does the word "first-born" decide the much-disputed question, whether Mary had any children to Joseph after the birth of Christ; for, as LIGHTFOOT says, "The law, in speaking of the first-born, regarded not whether any were born after or no, but only that none were born before." (See on Mat 13:55-56). Next: Matthew Chapter 2”