Augustine of Hippo — as excerpted in the Catena Aurea on John 6:52-54

“(super Joan. c. xxvi. 15) By this meat and drink then, He would have us understand the society of His body, and His members, which is the Church, in the predestined, and called, and justified, and glorified saints and believers. The Sacrament whereof, i. e. of the unity of the body and blood of Christ, is administered, in some places daily, in others on such and such days from the Lord’s Table: and from the Lord’s Table it is received by some to their salvation, by others to their condemnation. But the thing itself of which this is the Sacrament, is for our salvation to every one who partakes of it, for condemnation to none. To prevent us supposing that those who, by virtue of that meat and drink, were promised eternal life, would not die in the body, He adds, And I will, raise him up at the last day; i. e. to that eternal life, a spiritual rest, which the spirits of the Saints enter into. But neither shall the body be defrauded of eternal life, but shall be endowed with it at the resurrection of the dead in the last day.”