To distinguish His holiness from ours, Jesus is stated in an especial manner to be born holy. For we although indeed made holy, are not born so, for we are constrained by the very condition of our corruptible nature to cry out with the Prophet, Behold, I was conceived in iniquity. (Ps. 51:5.) But He alone is in truth holy, who was not conceived by the cementing of a fleshly union, nor as the heretics rave, one person in His human nature, another in His divine; not conceived and brought forth a mere man, and afterwards by his merits, obtained that He should be God, but the Angel announcing and the Spirit coming, first the Word in the womb, afterwards within the womb the Word made flesh. Whence it follows, Shall be called the Son of God.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: 18 Moral. c. 52. super <a href="/bible/job/28/19">Job 28:19</a>.