Against Celsus 1.35

But lest we seem to rest our assurance that the prophet said that the one at whose birth "God with us" was spoken would be born of a virgin on a Hebrew word, for those who cannot judge whether to accept it or not, come, let us establish the point from the text itself. The Lord is recorded to have said to Ahaz: "Ask for yourself a sign from the Lord your God, in the depth or in the height," and next comes the sign that is given: "Behold, the virgin will conceive in the womb and will bear a son." What sort of sign, then, would it be for a young woman who was not a virgin to give birth? And to whom is it more fitting to bear "Emmanuel," that is, "God with us"—to a woman who has had intercourse and conceived through a woman's passion, or to one still pure and chaste and a virgin? For it befits her to bear the offspring at whose birth "God with us" is said. And if he quibbles further, saying that it was said to Ahaz, "Ask for yourself a sign from the Lord your God," we will answer: Who was born in the time of Ahaz, at whose birth "Emmanuel, which is God with us" is said? If no one is to be found, clearly what was said to Ahaz was said to the house of David, because the Savior is recorded to have been born "of the seed of David according to the flesh." And this "sign" is said to be "in the depth or in the height," since "he who descended is the same one who also ascended far above all the heavens, that he might fill all things." I say this as to a Jew who accepts the prophecy. But let Celsus too, or one of those with him, say with what sort of mind the prophet speaks about the future, either these things or the others recorded in the prophecies: was it with a mind foreknowing the future or not? If with one foreknowing the future, the prophets had a divine spirit; if not, let him explain the mind of one who dares to speak about the future and is admired among the Jews for prophecy.