"If only a mere man was to be born of a pure virgin why should there be such careful mention of the divine arrival? Why such intervention of divinity itself? Certainly if only a man was to be born from man, and flesh from flesh, a command alone might have done it, or the divine will. For if the will of God alone, and His command sufficed to fashion the heavens, form the earth, create the sea, thrones, and seats, and angels, and archangels, and principalities, and powers, and in a word to create all the armies of heaven, and those countless thousands of thousands of the Divine hosts, 'For he spoke, and it came to be; he commanded, and it stood firm' (Ps 33:9), why was it that that was insufficient for the creation of (according to the Nestorians) a single man, which was sufficient for the production of all things divine, and that the power and majesty of God did not entrust that will with the birth of a single infant, which had sufficed to fashion all things earthly and heavenly? But certainly the reason why all those works were performed by the command of God, but the nativity was only accomplished by His coming was because God could not be conceived by man unless He allowed it, nor be born unless He Himself entered in. Therefore the archangel pointed out that the holy Majesty would come upon the Virgin. Because so great an event could not be brought about by human appointment, the archangel announced that there would be present at the conception the glory of Him who was to be born. So the Word, the Son, descended. The majesty of the Holy Spirit was present. The power of the Father was overshadowing that in the mystery of the holy conception the whole Trinity might cooperate. He says, 'Therefore the child to be born will be called holy- the Son of God' (Lk 1:35). Rightly does he add 'Therefore,' in order to show that this would therefore follow because that had gone before; and that because God had come upon her at the conception therefore God would be present at the birth.

 

"When the maiden did not understand, he gave a reason for this great thing, saying: 'The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy- the Son of God' (Lk 1:35), that is to say: That you might not be ignorant of the provision for so great a work, and the mystery of this great secret, the majesty of God shall therefore come upon you completely, because the Son of God shall be born of you. What further doubt can there be about this? What further is to be said? He said that God would come upon her; that the Son of God would be born. Ask now, if you like, how the Son of God can help being God, or how she who brought forth God can fail to be Theotokos, the Mother of God? This alone ought to be enough."