One more from Haydock’s Catholic commentary
Ver. 64.The flesh profiteth nothing.Dead flesh, separated from the spirit, in the gross manner they supposed they were to eat his flesh, would profit nothing. Neither doth man’s flesh, that is to say, man’s natural and carnal apprehension, (which refuses to be subject to the spirit, and words of Christ) profit any thing. But it would be the height of blasphemy, to say the living flesh of Christ (which we receive in the blessed sacrament, with his spirit, that is, with his soul and divinity) profiteth nothing. For if Christ’s flesh had profited us nothing, he would never have taken flesh for us, nor died in the flesh for us. —Are spirit and life.By proposing to you a heavenly sacrament, in which you shall receive, in a wonderful manner, spirit, grace and life. These words sufficiently correct the gross and carnal imagination of these Capharnaites, that he meant to give them his body and blood to eat in a visible and bloody manner, asflesh,says St. Augustine,is sold in the market, and in the shambles;[3] but they do not imply a figurative or metaphorical presence only. The manner of Christ’s presence is spiritual and under the outward appearances of bread and wine; but yet he is there truly and really present, by a change of the substance of bread and wine into the substance of his body and blood, whichtrulyandreallybecome our spiritual food, and are truly and really received in the holy sacrament. —The flesh[4] of itselfprofiteth nothing,not even the flesh of our Saviour Christ, were it not united to the divine person of Christ. But we must take care how we understand these words spoken by our Saviour: for it is certain, says St. Augustine, that theword made flesh,is the cause of all our happiness. (Witham) — When I promise you life if you eat my flesh, I do not wish you to understand this of that gross and carnal manner, of cutting my members in pieces: such ideas are far from my mind: the flesh profiteth nothing. In the Scriptures, the wordfleshis often put for the carnal manner of understanding any thing. If you wish to enter into the spirit of my words, raise your hearts to a more elevated and spiritual way of understanding them. (Calmet) — The reader may consult Des Mahis, p. 165, a convert from Protestantism, and who has proved the Catholic doctrine on the Eucharist in the most satisfactory manner, from the written word. Where he shows that Jesus Christ, speaking of his own body, never says*the flesh,butmy flesh:*the former mode of expression is used to signify, as we have observed above, a carnal manner of understanding any thing.Ver. 68.*Jesus said to the twelve: Will you also go away?*He shews them, says St. Chrysostom, that he stood not in need of them, and so leaves them to their free choice. (Witham) — Jesus Christ remarking in the previous verse that the apostate disciples had left him, to walk no more with him, turning to the twelve, asks them,*Will you also go away?The twelve had heard all that passed; they had seen the Jews strive amongst themselves, and the disciples murmur and leave their Master; they understood what he said in the same literal sense; it could, indeed, bear no other meaning; but when Jesus put the above question to them, leaving them to their free choice, whether to follow him, or to withdraw themselves, Simon Peter answered him: “Lord, to whom shall we go? Thou hast the words of eternal life;” and therefore art able to make good thy words, however hard and difficult they may appear to others. — We may here admire not only the excellency of their faith, but the plain, yet noble motive of their faith: they believe, because he is Christ, the Son of God, (or, as it is in the Greek, the Son of theliving God) who is absolutely incapable of deceiving his creatures, and whose power is perfectly equal to perform the promises he here makes them.Ver. 69.*Simon Peter,*the chief or head of them, said in the name of the rest:*Lord, to whom shall we go?It is only from thee that we hope for salvation.Thou hast the words of eternal life:we havebelieved, and known,and remain in this belief, thatthou art the Christ, the Son of God.(Witham)