Justin Martyr, First Apology 33
Once more, listen: as He Himself declared, Isaiah prophesied that He would be born of a virgin (Isaiah 7:14). The prophecy runs: "Behold, the virgin will have in her womb and will bear a son, and they will call his name Emmanuel, which is God with us." God foretold through the prophetic Spirit precisely those things that seemed unbelievable and impossible to human beings, so that when they come to pass they may not be disbelieved but believed because they were foretold. We will now try to clarify the words, lest anyone, failing to understand the stated prophecy, accuse us of the very thing we charged against the poets — that Zeus came to women for the sake of lust. The phrase "Behold, the virgin will have in her womb" means that the virgin conceived without intercourse; for if she had intercourse with anyone, she would no longer be a virgin. Instead, the power of God came upon the virgin, overshadowed her, and made her pregnant while she remained a virgin. The angel of God sent to the virgin at that time announced the good news to her, saying: "Behold, you will conceive in your womb from the Holy Spirit and bear a son, and he will be called the Son of the Most High, and you will call his name Jesus, for he will save his people from their sins." Those who remembered all things concerning our Savior Jesus Christ taught this, and we believed them, since even through Isaiah, the prophet previously mentioned, the prophetic Spirit said that He would be born in this way, as we have foretold. The Spirit, therefore, and the power from God are not to be understood as anything other than the Word, who is also the Firstborn of God, as Moses, the previously mentioned prophet, foretold; and this Word, coming upon the virgin and overshadowing her, not through intercourse but through power, made her pregnant. The name Jesus, in the Hebrew language, means Savior in the Greek dialect. From this the angel said to the virgin: "And you will call his name Jesus, for he will save his people from their sins." Since the prophets prophesy carrying no other god but the divine Word, you also, as I suppose, will agree.
Greek
Καὶ πάλιν ὡς αὐτολεξεὶ διὰ παρθένου μὲν τεχθησόμενος διὰ τοῦ Ἡσαΐου προεφητεύθη, ἀκούσατε. Ἐλέχθη δὲ οὕτως· „Ἰδοὺ ἡ παρθένος ἐν γαστρὶ ἕξει καὶ τέξεται υἱόν, καὶ ἐροῦσιν ἐπὶ τᾷ ὀνόματι αὐτοῦ Μεθ᾿ ἡμῶν ὁ θεός“. Ἃ γὰρ ἦν ἄπιστα καὶ ἀδύνατα νομιζόμενα παρὰ τοῖς ἀνθρώποις γενήσεσθαι, ταῦτα ὁ θεὸς προεμήνυσε διὰ τοῦ προφητικοῦ πνεύματος μέλλειν γίνεσθαι, ἵνα ὅταν γένηται μὴ ἀπιστηθῇ, ἀλλ᾿ ἐκ τοῦ προειρῆσθαι πιστευθῇ. Ὅπως δὲ μή τινες, μὴ νοήσαντες τὴν δεδηλωμένην προφητείαν, ἐγκαλέσωσιν ἡμῖν ἅπερ ἐνεκαλέσαμεν τοῖς ποιηταῖς, εἰποῦσιν ἀφροδισίων χάριν ἐληλυθέναι ἐπὶ γυναῖκας τὸν Δία, διασαφῆσαι τοὺς λόγους πειρασόμεθα. Τὸ οὖν „Ἰδοὺ ἡ παρθένος ἐν γαστρὶ ἕξει“ σημαίνει οὐ συνουσιασθεῖσαν τὴν παρθένον συλλαβεῖν· εἰ γὰρ ἐσυνουσιάσθη ὑπὸ ὁτουοῦν, οὐκ ἔτι ἦν παρθένος· ἀλλὰ δύναμις θεοῦ ἐπελθοῦσα τῇ παρθένῳ ἐπεσκίασεν αὐτήν, καὶ κυοφορῆσαι παρθένον οὖσαν πεποίηκε. Καὶ ὁ ἀποσταλεὶς δὲ πρὸς αὐτὴν τὴν παρθένον κατ᾿ ἐκεῖνο τοῦ καιροῦ ἄγγελος θεοῦ εὐηγγελίσατο αὐτὴν εἰπών· „Ἰδοὺ συλλήψῃ ἐν γαστρὶ ἐκ πνεύματος ἁγίου καὶ τέξῃ υἱόν, καὶ υἱὸς ὑψίστου κληθήσεται, καὶ καλέσεις τὸ ὄνομα αὐτοῦ Ἰησοῦν, αὐτὸς γὰρ σώσει τὸν λαὸν αὐτοῦ ἀπὸ τῶν ἁμαρτιῶν αὐτῶν“, ὡς οἱ ἀπομνημονεύσαντες πάντα τὰ περὶ τοῦ σωτῆρος ἡμῶν Ἰησοῦ Χριστοῦ ἐδίδαξαν, οἷς ἐπιστεύσαμεν, ἐπειδὴ καὶ διὰ Ἡσαΐου τοῦ προδεδηλωμένου τὸ προφητικὸν πνεῦμα τοῦτον γεννησόμενον, ὡς προεμηνύομεν, ἔφη. Τὸ πνεῦμα οὖν καὶ. τὴν δύναμιν τὴν παρὰ τοῦ θεοῦ οὐδὲν ἄλλο νοῆσαι θέμις ἢ τὸν λόγον, ὃς καὶ πρωτότοκος τῷ θεῷ ἐστι, Μωϋσῆς ὁ προδεδηλωμένος προφήτης ἐμήνυσε· καὶ τοῦτο ἐλθὸν ἐπὶ τὴν παρθένον καὶ ἐπισκιάσαν οὐ διὰ συνουσίας ἀλλὰ διὰ δυνάμεως ἐγκύμονα κατέστησε. Τὸ δὲ Ἰησοῦς, ὄνομα τῇ ἑβραΐδι φωνῇ, σωτὴρ τῇ ἑλληνίδι διαλέκτῳ δηλοῖ. Ὅθεν καὶ ὁ ἄγγελος πρὸς τὴν παρθένον εἶπε· „Καὶ καλέσεις τὸ ὄνομα αὐτοῦ Ἰησοῦν· αὐτὸς γὰρ σώσει τὸν λαὸν αὐτοῦ ἀπὸ τῶν ἁμαρτιῶν αὐτῶν“. Ὅτι δὲ οὐδενὶ ἄλλῳ θεοφοροῦνται οἱ προφητεύοντες εἰ μὴ λόγῳ θείῳ, καὶ ὑμεῖς, ὡς ὑπολαμβάνω, φήσετε.