16 But what say they? “We have baptism.” You have, but not yours. It is one thing to have, another to own. Baptism you have, for you have received to be baptized, received as one enlightened, provided you be not darkened of yourself; and when you give, you give as a minister, not as owner; as a herald proclaiming, not as a judge. The judge speaks through the herald, and nevertheless it is not written in the registers, “The herald said,” but, “The judge said.” Therefore see if what you give is yours by authority.
But if you have received, confess with the friend of the Bridegroom, “A man cannot receive anything, unless it be given him from heaven.” Confess with the friend of the Bridegroom, “He that has the bride is the Bridegroom; but the friend of the Bridegroom stands and hears Him.” But O, would you stood and hear Him, and not fall, to hear yourself! For by hearing Him, you would stand and hear; for you will speak, and your head is puffed with pride. I, says the Church, if I am the bride, if I have received pledges, if I have been redeemed at the price of that blood, do hear the voice of the Bridegroom; and I do hear the voice of the Bridegroom's friend too, if he give glory to my Bridegroom, not to himself.
Let the friend speak: “He that has the bride is the Bridegroom; but the friend of the Bridegroom stands and hears Him, and rejoices greatly because of the voice of the Bridegroom.” Behold, you have sacraments; and I grant that you have. You have the form, but you are a branch cut off from the vine; you have a form, I want the root. There is no fruit of the form, except where there is a root; but where is the root but in charity? Hear the form of the cut-off branches; let Paul speak: “Though I know all mysteries,” says he, “and have all prophecy, and all faith” (and how great a faith!), “so as to remove mountains, and have not charity, I am nothing.”
Source: Tractates on the Gospel of John (New Advent)