Augustine of Hippo
Catena Aurea · Johannesevangelium 15
I am the true vine, and my Father is the husbandman. Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit. Now ye are clean through the word which I have spoken unto you.
(Tr. lxxx. 2) He says this as being the Head of the Church, of which we are the members, the Man Christ Jesus; for the vine and the branches are of the same nature. When He says, I am the true vine, He does not mean really a vine; for He is only called so metaphorically, not literally, even as He is called the Lamb, the Sheep, and the like; but He distinguishes Himself from that vine to whom it is said, How art thou turned into the degenerate plant of a strange vine unto me. (Jer. 11:21) For how is that a true vine, which when grapes are expected from it, produces only thorns?