Justin Martyr, First Apology 33
Once again, just as it was spoken by himself, it was foretold through Isaiah that he would be born through a virgin; listen. It was spoken in this way: "Behold, the virgin will conceive and bear a son, and they will call his name Emmanuel," which means "God with us" (Isaiah 7:14). For the things that were considered unbelievable and impossible among human beings, God foretold through the prophetic Spirit that they were going to happen, so that when they do happen they will not be disbelieved, but will be believed precisely because they were foretold. We will also try to explain the words so that certain people, failing to understand the prophecy that has been spoken, may not accuse us of the very thing we accused the poets of, namely, saying that Zeus came to women for the sake of lust. The statement "Behold, the virgin will conceive" means that the virgin conceived without having intercourse; for if she had intercourse with anyone, she would no longer be a virgin. Rather, the power of God came upon the virgin and overshadowed her, and made her pregnant while she remained a virgin. And 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 will 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" (Matthew 1:21), just as those who remembered all things about our Savior Jesus Christ taught, and we believed them, since through Isaiah, the prophetic Spirit foretold that this one was going to be born, as we declared beforehand. The Spirit, therefore, and the power from God, it is not right to understand as anything other than the Word, who is also the firstborn of God, as Moses, the foretold prophet, foretold; and this Word, having come upon the virgin and overshadowed her, made her pregnant not through intercourse but through power. And the name Jesus, in the Hebrew language, means Savior in the Greek dialect. From this the angel also said to the virgin: "And you will call his name Jesus, for he will save his people from their sins." That the prophets prophesy carried by no other than the divine Word, you also, as I suppose, will say.
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.