Augustine on Christ, writing to a student of his.

Begotten and conceived, then, without any indulgence of carnal lust, and therefore bringing with Him no original sin, and by the grace of God joined and united in a wonderful and unspeakablr way in one person with the Word, thr Only-begotten of the Father, a son by nature, not by grace, and therefore having no sin of His own; nevertheless, on account of the likeness of sinful flesh in which He came, He was called sin, that He might be sacrificed to wash away sin.