The sacred Evangelist says that Mary was betrothed to Joseph, to shew that the conception had taken place upon her betrothal solely, and that the birth of the Emanuel was miraculous, and not in accordance with the laws of nature. For the holy Virgin did not bear from the immission of man’s seed. And what was the reason of this? Christ, Who is the first-fruits of all, the second Adam according to the Scriptures, was born of the Spirit, that he might transmit the grace (of the spiritual birth) to us also: for we too were intended, no longer to bear the name of sons of men, but of God rather, having obtained the new birth of the Spirit in Christ first, that he might be “foremost among all,” as the most wise Paul declares. — Commentary on Luke II.