Catena Aurea on Matthew 1:20: Augustine of Hippo

But shall we therefore say that the Holy Spirit is the Father of the man Christ, that as God the Father begot the Word, so the Holy Spirit begot the man? This is such an absurdity, that the ears of the faithful cannot bear it.

How then do we say that Christ was born by the Holy Spirit, if the Holy Spirit did not beget Him? Did He create Him? For so far as He is man He was created, as the Apostle speaks; “He was made of the seed of David according to the flesh.” [Rom 1:3] 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.