Christ was born of the Holy Spirit and the Virgin, not of a man's seed
Gregory condemns the view that Christ was conceived from a man's seed, and answers from the angel's words to Mary and to Joseph.
If anyone says that Christ was begotten of the Virgin from the seed of a man, as all other men are born, and does not confess that he was incarnate of the Holy Spirit and of holy Mary the Virgin, and became man from the seed of David (Romans 1:3), as it is written, let him be anathema.
How can it be said that Christ was begotten of the Virgin from the seed of a man, when the holy Gospel and the angel himself testify that the Virgin Mary said, “How will this happen to me, since I do not know a man?” (Luke 1:34) That is why the one who brought the news to Mary said, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you. Therefore the holy one who is born of you will be called Son of the Most High” (Luke 1:35). And to Joseph he says, “Do not be afraid to take Mary as your wife, for what has been begotten in her is from the Holy Spirit. She will bear a son, and they will call his name Jesus, for he will save his people from their sins” (Matthew 1:20–21).
Latin
Si quis dicat ex semine viri genitum esse Christum de Virgine, sicut omnes alii nascuntur homines; et non confitetur ipsum ex Spiritu sancto, et ex sancta Maria virgine incarnatum, et factum hominem ex semine David, sicut scriptum est; anathema sit. Quomodo dici potest ex semine viri genitus Christus ex Virgine; cum sanctum Evangelium, et ipse Angelus testentur, Mariam Virginem dixisse: Quomodo fiet mihi istud; quoniam virum non cognosco? Ideo et qui nuntiavit Mariae, dixit: Spiritus sanctus superveniet in te, et virtus Altissimi obumbrabit tibi. Quamobrem et quod natum est ex te sanctum, vocabitur filius Altissimi. Et Iosepho dicit: Ne timeas accipere Mariam coniugem tuam. Quod enim in ea natum est, ex Spiritu sancto est: pariet vero filium, et vocabunt nomen eius Iesum. Ipse enim salvum faciet populum suum a peccatis eorum.