Augustine of Hippo — as excerpted in the Catena Aurea on John 6:55-59

“(Tr. xxvi. s. 19) He saith not, As I eat the Father, and live by the Father, so he that eateth Me, even he shall live by Me. For the Son does not grow better by partaking of the Father, as we do by partaking of the Son, i. e. of His one body and blood, which this eating and drinking signifies. So that His saying, I live by the Father, because He is from Him, must not be understood as detracting from His equality. Nor do the words, Even he that eateth Me, the same shall live by Me, give us the equality that He has. He does not equalize, but only mediates between God and man. If, however, we understand the words, I live by the Father, in the sense of those below, My Father is greater than I, (c. 14:28) then it is as if He said, That I live by the Father, i. e. refer my life to Him, as my superior, my1 humiliation in my incarnation is the cause; but He who lives by Me, lives by Me by virtue of partaking of My flesh.”