But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, son of David, fear not to take unto you Mary your wife: for that which is conceived in her is of the Holy Spirit.
All Commentaries on Matthew 1:20 Go To Matthew 1
Augustine of Hippo
Yet though Joseph think on these things, let not Mary the daughter of David be troubled; as the word of the Prophet brought pardon to David, so the Angel of the Saviour delivers Mary. Behold, again appears Gabriel the brides man of this Virgin; as it follows, “Behold the Angel of the Lord appeared to Joseph.”
But if Christ was born by the agency of the Holy Spirit, how is that said, “Wisdom hath built herself an house?” For though God made the world, yet is it not right to say that it is the Son of God, or born by Him, but that it was made, or created, or formed by Him. But seeing that we confess Christ to have been born by the Holy Spirit, and of the Virgin Mary, how is He not the Son of the Holy Spirit, and is the Son of the Virgin? It does not follow, that whatever is born by any thing, is therefore to be called the son of that thing; for, not to say that of man is born in one sense a son, in another a hair, or vermin, or a worm, none of which are his son, certainly those that are born of water and the Spirit none would call sons of water; but sons of God their Father, and their Mother the Church. Thus Christ was born of the Holy Spirit, and yet is the Son of God the Father, not of the Holy Spirit.