John Gill's Exposition of the Whole Bible
Matthew 1:18
Now the birth of Jesus Christ,.... The Evangelist having finished the genealogy of Christ, proceeds to give an account of his birth, which includes both his conception and bringing forth; and which he says
was on this wise, f1 ουτως so, "after this manner", and which was very wonderful and astonishing;
when as, f1 γαρ, for his mother Mary was found with child,, not of man, no, not of Joseph her husband; Christ had no real father as man, Joseph was only, as was supposed, his father; but
of the Holy Ghost, according to Luke 1:35. "The Holy Ghost shall come upon thee", c. and this was done that the human nature of Christ might be clear of original pollution that so being the immediate produce of the Holy Ghost and without sin, it might be fit for union with the Son of God, and for the office of Mediator he had undertook. When Mary is said to be
found with child, the meaning is, it appeared by evident signs, it was observed by Joseph particularly, who might know not only that she was with child, but with child of the Holy Ghost; by conversation with her, who might relate to him what passed between the Angel and her, Luke 1:28 though it looks as if as yet he did not know this, or at least was not fully satisfied about it; since he had a mind to have put her away, before he was assured of the truth of it, by the appearance of an angel to him. Now Mary's being with child, and its being known, were facts, at the time when she was
espoused to Joseph, and thereby the outward credit both of Mary and Jesus were secured; for had this appeared before the espousals, the Jews would have fixed a brand of infamy on them both; and both the espousals and her being found with child, were
before they came together; that is, before they cohabited together as man and wife, before he brought her home to his own house and bed. The espousals were before they thus came together. It was usual with the Jews first to espouse or betroth, and then to marry, or rather consummate the marriage, by bringing the woman home to her husband's house, between which there was some space of time. The account and manner of betrothing is given by Maimonides y in the following words.
"Before the giving of the law, if a man met a woman in the street, if he would, he might take her, and bring her into his house and marry her between him and herself, and she became his wife; but when the law was given, the Israelites were commanded, that if a man would take a woman he should obtain her before witnesses, and after that she should be his wife, according to Deuteronomy 22:13 and these takings are an affirmative command of the law, and are called או אירוסין
קידושין "espousals" or "betrothings" in every place; and a woman who is obtained in such a way is called או מאורסת
מקודשת "espoused" or "betrothed"; and when a woman is obtained, and becomes מקודשת "espoused", although she is not yet נבעלה "married, nor has entered into her husband's house", yet she is a man's wife.''
And such a distinction between a married woman and a betrothed virgin, which was Mary's case, may be observed in Deuteronomy 22:22 moreover, her being found or appearing to be with child, was "before they came together"; which it is likely, as Dr. Lightfoot z observes, was about three months from her conception, when she was returned from her cousin Elizabeth. It is probable that as soon as she was espoused to Joseph, or quickly after, she went and paid her visit to Elizabeth, with whom she stayed about three months, and then returned home, Luke 1:56. Upon her return home, she appears to be with child, with which she had gone three months, a proper time for the discovery of such a matter, Genesis 38:24 and which is assigned by the Jewish doctors for this purpose. In the Misna a such a case as this is put,
"If two men should espouse two women, and at the time of their entrance into the bride chamber, the one should be taken for the other--they separate them for three months, because they may prove with child;''
that is, as Bartenora observes upon it,
"they separate them that they may not return to their husbands; and that if they should be with child, they may distinguish between a legitimate and an illegitimate offspring; and that the children which they may bring forth may not be ascribed to the wrong persons.''
Now Mary being gone three months from the time of her espousals to Joseph, and he and she not being yet come together, it was a clear case, that the child she was gone three months with, was none of his; hence it follows,
y Hilchot. Ishot. c. 1. sect. 1, 2, 3. z In loc. a Yebamot, c. 3. sect. 10.