6 “He came unto His own;” that is to say, He came to that which belonged to Himself; “and His own received Him not.” What, then, is the hope, unless that “as many as received Him, to them gave He power to become the sons of God”? If they become sons, they are born; if born, how are they born? Not of flesh, “nor of blood, nor of the will of the flesh, nor of the will of man; but of God are they born.” Let them rejoice, therefore, that they are born of God; let them believe that they are born of God; let them receive the proof that they are born of God: “And the Word became flesh, and dwelt among us.” If the Word was not ashamed to be born of man, are men ashamed to be born of God? And because He did this, He cured us; and because He cured us, we see. For this, “that the Word was made flesh, and dwelt among us,” became a medicine unto us, so that as by earth we were made blind, by earth we might be healed; and having been healed, might behold what? “And we beheld,” he says, “His glory, the glory as of the Only-begotten of the Father, full of grace and truth.”
Source: Tractates on the Gospel of John (New Advent)