If your parish uses "individual wafers" for Eucharistic bread, you'd best substitute another passage for Sunday's second reading (I Cor 10: 16-17).
Back to that issue later. In the meantime, it's easy to see how the first and third readings relate to one another. The Gospel (Jn 6: 51-58) makes sense only when we know the event to which Moses refers in the first reading (Dt 8: 2-3, 14-16).
Reminding his people about their experience of wilderness wandering, the great Jewish liberator states, God "let you be afflicted with hunger and then fed you with manna, a food unknown to you and your ancestors, in order to show you that not by bread alone does one live, but by every work that comes forth from the mouth of the Lord."
Just as deliverance from saraph serpents and water flowing from a rock demonstrated Yahweh's great love for a group of homeless Israelites, so manna from heaven became synonymous for the concern God has for those who give themselves over to God.
Presuming this, and building on a belief that anything Yahweh did for Jews, Yahweh (through Jesus) does better for Christians, John stresses the life-giving dimension of consuming His body and blood.
"I am the living bread that came down from heaven; whoever eats this bread will live forever, and the bread I will give is my flesh for the life of the world....Unlike your ancestors who ate and still died, whoever eats this bread will live forever."
The image is clear; the theology well-known. There's no need to expound on it here. On the other hand, the image and theology in the second reading is certainly clear, but not very well-known. Written more than 10 years before Mark composed the first Gospel, this is the earliest explicit reference to the Eucharist in Christian literature, found one chapter before Paul's Last Supper account in I Corinthians 11.
Paul didn't write these lines because he wanted to instruct his people on the Eucharist. He simply was concerned with issues dividing the Corinthian church, especially questions about eating food once offered to idols. Reminding his readers that they're united in sharing both the cup of blessing and the Eucharistic bread, he states, the cup is "a participation in the blood of Christ;" the bread is "a participation in the body of Christ."
But then he goes one step further: "Because the loaf of bread is one, we, though many, are one body, for we all partake of the one loaf." The Eucharist actually helps create unity by offering us one loaf of bread to eat. The one loaf is a sign that all who consume it are one.
For Paul, our participation in the blood and body of Christ is a unifying element. The outward signs of one bread and one cup remind us to sacrifice our own "body and blood" in the process of becoming one with all who join us in the celebration.
In preparation for First Communion, most of us were taught that receiving the Eucharist was "something between Jesus and me." Other people present during the celebration were simply occasions of sinful distraction, temptations leading us away from concentrating on Jesus. Paul never would have understood such a theology.
But one of the sad remnants of that teaching is our common practice of having neat, individual servings instead of a cumbersome, sometimes messy, loaf of bread. Paul believes that forming community is just as cumbersome and messy as the one loaf used in his churches. Yet it's a commitment all Christians should make.
BY the way, if you choose to replace the second reading with another, there's one problem: I don't know of any passage from the Christian Scriptures that defends the use of individual servings.