Augustine of Hippo
Catena Aurea · Johannesevangelium 15
Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me. I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned. If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you.
(Tract. lxxxi. 1) Abide in Me, and I in you: not they in Him, as He in them; for both are for the profit not of Him, but them. The branches do not confer any advantage upon the vine, but receive their support from it: the vine supplies nourishment to the branches, takes none from them: so that the abiding in Christ, and the having Christ abiding in them, are both for the profit of the disciples, not of Christ; according to what follows, As the branch cannot bear fruit of itself, except it abide in the vine, no more can ye, except ye abide in Me. Great display of grace! He strengtheneth the hearts of the humble, stoppeth the mouth of the proud. They who hold that God is not necessary for the doing of good works, the subverters, not the assertors, of free will, contradict this truth. For he who thinks that he bears fruit of himself, is not in the vine; he who is not in the vine, is not in Christ; he who is not in Christ, is not a Christian.