Alcuin
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.
All the fruit of good works proceeds from this root. He who hath delivered us by His grace, also carries us onward by his help, so that we bring forth more fruit. Wherefore He repeats, and explains what He has said: I am the vine, ye are the branches. He that abideth in Me, by believing, obeying, persevering, and I in Him, by enlightening, assisting, giving perseverance, the same, and none other, bringeth forth much fruit.