John Chrysostom — as excerpted in the Catena Aurea on Matthew 1:18

“He says exactly was found, for so we use to say of things not thought of. And that you should not molest the Evangelist by asking in what way was this birth of a virgin, he clears himself shortly, saying, Of the Holy Ghost. As much as to say, it was the Holy Ghost that wrought this miracle. For neither Gabriel nor Matthew could say any further.”