Luke 1:34,35

Then said Mary unto the angel, &c.— When Mary heard Gabriel say that she was to conceive the Messiah, being conscious of her virginity, she found the matter above her comprehension, and therefore desired him to explain it. Being young and unexperienced, it was not to be expected that she could have a comprehension of mind and strength of faith equal to that which the old priest Zacharias ought to have possessed. Besides, this was a thing supernatural, and altogether without example. For though it is not distinctly mentioned by the evangelist, it is plain from Mary's answer that the angel had informed her that the whole would be perfectly supernatural. These seem to have been the reasons why Gabriel, who had struck Zacharias dumb for presuming to ask a sign in proof of his wife's future pregnancy, bore with the virgin when she desired to know how her's could be brought about. In the mean time it should be observed, that Mary did not, like Zacharias, insinuate that she would not believe till a miracle was wrought to convince her, but only that she did not understand how her pregnancy could be effected in her virgin state, and desired him to explain it to her, not doubting but it was possible. Wherefore the weakness of her apprehension being consistent with faith, and her request being conceived with modesty and humility, the angel told her that the wonderful event should be accomplished by the interposition of the Holy Spirit, and special energy of the power of God, who would preserve her reputation entire, at least in the opinion of impartial judges, and protect her from any inquiry to which this mystery might expose her; for, by the Jewish law, a severe punishment was inflicted on women betrothed, who proved with child before they lived with their husbands. This protection, perhaps, may be implied in the phrase, overshadow thee. To be under the shadow of wings, is a phrase used in the Psalms to express the tender affection with which God preserves his servants. But if the passage be only exegetical of the preceding clause, there may be a reference perhaps to Genesis 1:2 where the spirit of God is represented, as brooding or hovering over chaos; which Milton expresses thus:

——Thou from the first Wast present, and with mighty wings outspread, Dove-like, sat'st brooding on the vast abyss, And mad'st it pregnant. Par. Lost, B. 1: Luke 1:19.

It is added, That holy thing which shall be born of thee shall be called—that is, shall be, the Son of God; because thou shalt conceive him by the immediate operation of the Holy Ghost, causing him to exist in thy womb. The term, Το γεννωμενον, in the neuter gender, denotes the human nature of Christ derived from his virgin mother:—born of thee.