5 Where was it? Was it here? Was it with the Father, and was it not here? Or, what is more true, was it both with the Father and here also? If then it was here, wherefore was it not seen? Because “the light shines in darkness, and the darkness comprehended it not.” Oh men, be not darkness, be not unbelieving, unjust, unrighteous, rapacious, avaricious lovers of this world: for these are the darkness. The light is not absent, but you are absent from the light. A blind man in the sunshine has the sun present to him, but is himself absent from the sun. Be not then darkness. For this is perhaps the grace regarding which we are about to speak, that now we be no more darkness, and that the apostle may say to us, “We were sometime darkness, but now light in the Lord.” Because then the light of men was not seen, that is, the light of minds, there was a necessity that a man should give testimony regarding the light, who was not in darkness, but who was already enlightened; and nevertheless, because enlightened, not the light itself, “but that He might bear witness of the light.” For “he was not that light.” And what was the light? “That was the true light which enlightened every man that comes into the world.” And where was that light? “In this world it was.” And how was it “in this world?” As the light of the sun, of the moon, and of lamps, was that light thus in the world? No. Because “the world was made by Him, and the world knew Him not;” that is to say, “the light shines in darkness, and the darkness comprehended it not.” For the world is darkness; because the lovers of the world are the world. For did not the creature acknowledge its Creator? The heavens gave testimony by a star; the sea gave testimony, and bore its Lord when He walked upon it; the winds gave testimony, and were quiet at His bidding; the earth gave testimony, and trembled when He was crucified. If all these gave testimony, in what sense did the world not know Him, unless that the world signifies the lovers of the world, those who with their hearts dwell in the world? And the world is evil, because the inhabitants of the world are evil; just as a house is evil, not because of its walls, but because of its inhabitants.
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.”
7. “John bears witness of Him, and cries, saying, This was He of whom I spoke, He that comes after me is made before me.” He came after me, and He preceded me. What is it, “He is made before me”? He preceded me. Not was made before I was made, but was preferred before me, this is “He was made before me.” Wherefore was He made before you, when He came after you? “Because He was before me.” Before you, O John! What great thing to be before you! It is well that you bear witness to Him; let us, however, hear Himself saying, “Even before Abraham, I am.” But Abraham also was born in the midst of the human race: there were many before him, many after him. Listen to the voice of the Father to the Son: “Before Lucifer I have begotten You.” He who was begotten before Lucifer Himself illuminates all. A certain one was named Lucifer, who fell; for he was an angel and became a devil; and concerning him the Scripture said, “Lucifer, who did arise in the morning, fell.” And why was he Lucifer? Because, being enlightened, he gave forth light. But for what reason did he become dark! Because he abode not in the truth. Therefore He was before Lucifer, before every one that is enlightened; since before every one that is enlightened, of necessity He must be by whom all are enlightened who can be enlightened.
Source: Tractates on the Gospel of John (New Advent)