Origen — Contra Celsum 1.35
But that we may not seem, because of a Hebrew word, to endeavour to persuade those who are unable to determine whether they ought to believe it or not, that the prophet spoke of this man being born of a virgin, because at his birth these words, God with us, were uttered, let us make good our point from the words themselves. The Lord is related to have spoken to Ahaz thus: Ask a sign for yourself from the Lord your God, either in the depth or height above; and afterwards the sign is given, Behold, a virgin shall conceive, and bear a son.
What kind of sign, then, would that have been — a young woman who was not a virgin giving birth to a child? And which of the two is the more appropriate as the mother of Immanuel (i.e., God with us) — whether a woman who has had intercourse with a man, and who has conceived after the manner of women, or one who is still a pure and holy virgin? Surely it is appropriate only to the latter to produce a being at whose birth it is said, God with us.
And should he be so captious as to say that it is to Ahaz that the command is addressed, Ask for yourself a sign from the Lord your God, we shall ask in return, who in the times of Ahaz bore a son at whose birth the expression is made use of, Immanuel, i.e., God with us? And if no one can be found, then manifestly what was said to Ahaz was said to the house of David, because it is written that the Saviour was born of the house of David according to the flesh; and this sign is said to be in the depth or in the height, since He that descended is the same also that ascended up far above all heavens, that He might fill all things.
And these arguments I employ as against a Jew who believes in prophecy. Let Celsus now tell me, or any of those who think with him, with what meaning the prophet utters either these statements about the future, or the others which are contained in the prophecies? Is it with any foresight of the future or not? If with a foresight of the future, then the prophets were divinely inspired; if with no foresight of the future, let him explain the meaning of one who speaks thus boldly regarding the future, and who is an object of admiration among the Jews because of his prophetic powers.
Greek
Ἵνα δὲ μὴ δοκῶμεν ἀπὸ λέξεως Ἑβραϊκῆς τοῖς μὴ καταλαμβάνουσι, πότερον συγκαταθετέον αὐτῇ ἢ μὴ, φέρειν παραμυθίαν περὶ τοῦ προφήτην εἰρηκέναι ἐκ παρθένου τεχθήσεσθαι τοῦτον, ἐφ᾿ οὗ τῇ γενέσει λέλεκται τὸ „μεθ᾿ ἡμῶν ὁ θεὸς“, φέρε ἐπ᾿ αὐτῆς τῆς λέξεως παραμυθησώμεθα τὸ λεγόμενον. ὁ μὲν κύριος ἀναγέγραπται εἰρηκέναι τῷ Ἄχαζ· „αἴτησαι σεαυτῷ σημεῖον παρὰ κυρίου τοῦ θεοῦ σου εἰς βάθος ἢ εἰς ὕψος,“ ἑξῆς δὲ τὸ διδόμενον σημεῖον τὸ „ἰδοὺ ἡ παρθένος ἐν γαστρὶ ἕξει καὶ τέξεται υἱόν.“ ποῖον οὖν σημεῖον τὸ νεάνιδα, μὴ παρθένον τεκεῖν; καὶ τίνι μᾶλλον ἁρμόζει γεννῆσαι „Ἐμμανουὴλ,“ τουτέστι „μεθ᾿ ἡμῶν ὁ θεὸς,“ ἆρα γυναικὶ συνουσιασθείσῃ καὶ διὰ πάθους γυναικείου συλλαβούσῃ ἢ ἔτι καθαρᾷ καὶ ἁγνῇ καὶ παρθένῳ; ταύτῃ γὰρ πρέπει γεννᾶν γέννημα, ἐφ᾿ ᾧ τεχθέντι λέγεται τὸ „μεθ᾿ ἡμῶν ὁ θεός.“ ἐὰν δὲ καὶ οὕτως εὑρεσιλογῇ λέγων ὅτι τῷ Ἄχαζ εἴρηται· „αἴτησαι σεαυτῷ σημεῖον παρὰ κυρίου τοῦ θεοῦ σου,“ ἀπαντήσομεν· κατὰ τοὺς χρόνους τοῦ Ἄχαζ τίς ἐγεννήθη, ἐφ᾿ οἷ τῇ γενέσει λέγεται τὸ „Ἐμμανουὴλ, ὅ ἐστι μεθ᾿ ἡμῶν ὁ θεός,·“ εἰ γὰρ οὐδεὶς εὑρεθήσεται, δηλονότι τὸ τῷ Ἄχαζ εἰρημένον τῷ οἴκῳ εἴρηται Δαυὶδ διὰ τὸ „ἐκ σπέρματος Δαυὶδ“ ἀναγεγράφθαι τὸν σωτῆρα γεγονέναι „τὸ κατὰ σάρκα“· ἀλλὰ καὶ τὸ „σημεῖον“ τοῦτο „εἰς βάθος ἢ εἰς ὕψος“ λέγεται εἶναι, ἐπεὶ „ὁ καταβὰς οὗτός ἐστι καὶ ὁ ἀναβὰς ὑπεράνω πάντων τῶν οὐρανῶν, ἵνα πληρώσῃ τὰ πάντα.“ ταῦτα δὲ λέγω ὡς πρὸς τὸν Ἰουδαῖον συγκατατιθέμενον τῇ προφητείᾳ. λεγέτω δὲ καὶ Κέλσος ἤ τις τῶν σὺν αὐτῷ, ποίῳ νῷ ὁ προφήτης περὶ μελλόντων ἢ ταῦτα ἢ ἕτερα λέγει, ὁπόσα ἀναγέγραπται ἐν ταῖς προφητείαις· ἆρα γὰρ προγνωστικῷ μελλόντων ἢ οὔ; εἰ μὲν γὰρ προγνωστικῷ μελλόντων, θεῖον εἶχον πνεῦμα οἱ προφῆται· εἰ δ᾿ οὐ προγνωστικῷ μελλόντων, παραστησάτω τὸν νοῦν τοῦ ἀποτολμῶντος καὶ λέγοντος περὶ μελλόντων καὶ θαυμαζομένου παρὰ τοῖς Ἰουδαίοις ἐπὶ προφητείᾳ.