Augustine of Hippo
Catena Aurea · Johannesevangelium 6
For my flesh is meat indeed, and my blood is drink indeed. He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him. As the living Father hath sent me, and I live by the Father: so he that eateth me, even he shall live by me. This is that bread which came down from heaven: not as your fathers did eat manna, and are dead: he that eateth of this bread shall live for ever. These things said he in the synagogue, as he taught in Capernaum.
(de Verb. Dom.) As for those, as indeed there are many, who either eat that flesh and drink that blood hypocritically, or, who having eaten, become apostates, do they dwell in Christ, and Christ in them? Nay, but there is a certain mode of eating that flesh, and drinking that blood, in the which he that eateth and drinketh, dwelleth in Christ, and Christ in him.