Tractates on the Gospel of John

³ Now this is what follows: and John says, “This my joy therefore is fulfilled.” What is his joy? To rejoice at the Bridegroom's voice. It is fulfilled in me, I have my grace; more I do not assume to myself, lest also I lose what I have received. What is this joy? “With joy rejoices for the Bridegroom's voice.” A man may understand, then, that he ought not to rejoice of his own wisdom, but of the wisdom which he has received from God. Let him ask nothing more, and he loses not what he found. For many, in that they affirmed themselves to be wise, became fools. The apostle convicts them, and says of them, “Because that which is known of God is manifest to them; for God has showed it unto them.” Hear ye what he says of certain unthankful, ungodly men: “For the invisible things of Him from the creation of the world are seen, being understood by the things that are made, His eternal power likewise, and Godhead; so that they are without excuse.” Why without excuse? “Because, knowing God” (he said not, “because they knew Him not”), “they glorified Him not as God, nor were thankful; but became vain in their imaginations, and their foolish heart was darkened: professing themselves to be wise, they became fools.” If they had known God, they had known at the same time that God, and none other, had made them wise; and they would not then attribute to themselves that which they did not have from themselves, but to Him from whom they had received it. But by their unthankfulness they became fools. Therefore, what God gave freely, He took from the unthankful. John would not be this; he would be thankful: he confessed to have received, and declared that he rejoiced for the Bridegroom's voice, saying, “Therefore this my joy is fulfilled.”

4. “He must increase, but I must decrease.” What is this? He must be exalted, but I must be humbled. How is Jesus to increase? How is God to increase? The perfect does not increase. God neither increases nor decreases. For if He increases, He is not perfect; if He decreases, he is not God. And how can Jesus increase, being God? If to man's estate, since He deigned to be man and was a child; and, though the Word of God, lay an infant in a manger; and, though His mother's Creator, yet sucked the milk of infancy of her: then Jesus having grown in age of the flesh, that perhaps is the reason why it is said, “He must increase, but I must decrease.” But why in this? As regards the flesh, John and Jesus were of the same age, there being six months between them: they had grown up together; and if our Lord Jesus Christ had willed to be here longer before His death, and that John should be here with Him, then, as they had grown up together, so would they have grown old together: in what way, then, “He must increase but I must decrease”? Above all, our Lord Jesus Christ being now thirty years old, does a man who is already thirty years old still grow? From that same age, men begin to go downward, and to decline to graver age, thence to old age. Again, even had they both been lads, he would not have said, “He must increase,” but, We must increase together. But now each is thirty years of age. The interval of six months makes no difference in age; the difference is discovered by reading rather than by the look of the persons.