“Moreover, the prophecy, Behold, the virgin shall conceive, and bear a son, was uttered respecting Him. For if He to whom Isaiah referred was not to be begotten of a virgin, of whom 2279 did the Holy Spirit declare, Behold, the Lord Himself shall give us a sign: behold, the virgin shall conceive, and bear a son? For if He also were to be begotten of sexual intercourse, like all other first-born sons, why did God say that He would give a sign which is not common to all the first-born sons? But that which is truly a sign, and which was to be made trustworthy to mankind,—namely, that the first-begotten of all creation should become incarnate by the Virgins womb, and be a child,—this he anticipated by the Spirit of prophecy, and predicted it, as I have repeated to you, in various ways; in order that, when the event should take place, it might be known as the operation of the power and will of the Maker of all things; just as Eve was made from one of Adams ribs, and as all living beings were created in the beginning by the word of God. But you in these matters venture to pervert the expositions which your elders that were with Ptolemy king of Egypt gave forth, since you assert that the Scripture is not so as they have expounded it, but says, Behold, the young woman shall conceive, as if great events were to be inferred if a woman should beget from sexual intercourse: which indeed all young women, with the exception of the barren, do; but even these, God, if He wills, is able to cause [to bear]. For Samuels mother, who was barren, brought forth by the will of God; and so also the wife of the holy patriarch Abraham; and Elisabeth, who bore John the Baptist, and other such. So that you must not suppose that it is impossible for God to do anything He wills. And especially when it was predicted that this would take place, do not venture to pervert or misinterpret the prophecies, since you will injure yourselves alone, and will not harm God.
Or, “why was it.”