In every prophecy, not everything is understood before it is fulfilled. Yet one cannot say that because of this property prophecy is unnecessary.
So too the Lord's prophecy about the Eucharist became fully intelligible to every believer after its fulfillment. Yet even before fulfillment, as the promise of a lofty benefit, it was consoling.
It raised faith in Jesus the Messiah, Who promised to send a food greater than the manna of Moses' time.
"He who eats My Flesh and drinks My Blood abides in Me, and I in him." This explains the words, "My Flesh is truly food."
As material food and material drink become the possession of the bodily organism, so the one who eats the Body of Christ and drinks His Blood will appropriate Christ the Lord to himself.
This is not the same as moral appropriation of oneself to Christ. It is a real appropriation of the Lord, dependent on the Lord's will.
Saint Hilary writes: "If the Word became flesh, and in food we receive the Lord, the Word truly become flesh, how does He not abide naturally in us? He was born as man, assumed our whole nature, and in the Mystery communicates to us flesh united with the eternal nature."
Those who eat My Flesh will enjoy the same blessed life by which "I live through the Father Who sent Me," says the Lord.
Since the life of the Sent One is spoken of here, one must understand not the pre-eternal life of the Son, but the life of the Messiah. Saint Cyril of Alexandria understood it in this way.