My husband loved to take our children fishing, so they've understood since they were very young that when we eat fish, we're eating something that was, not long ago, a living, breathing creature. My youngest son went bison hunting with his school class when he was 12 or so. They got their bison, helped butcher it, and served it fresh as bison burgers at a community feast. These children knew from experience that burgers don't come from a fast food joint—ultimately, anyway—but from living animals killed so we can eat burgers made from their flesh.
Berry picking and gardening taught a similar lesson. The lettuce lived and grew until we picked it to put in our salad. The raspberries ripened on the bush until we plucked them for our buckets. Lettuce and berries, like most food, were living things that died so we could eat.
Human life is sustained by the nourishment that comes from living things that die. D. A. Carson uses this principle from the natural world to explain the mysterious words of Jesus recorded in John 6:
I am the bread of life . . . .
I am the living bread that came down from heaven. If anyone eats of this bread, he will live forever. And the bread that I will give for the life of the world is my flesh. . . . [U]nless you eat the flesh of the Son of Man and drink his blood, you have no life in you.” (John 6:35, 51, 53 ESV)Here's what Carson writes:
Jesus says he is the Bread of Life and unless we eat him we will die. At a superficial level, the notion of eating Jesus might sound jolly close to cannibalism. Or those of us who are more religiously inclined might think, "Maybe it's the sacrament of holy communion or something like that." Originally, that was not what Jesus meant at all. We must not forget that in the ancient world just about everybody worked with their hand or on farms, so they were closer to nature than we are today. . . . [I]f you were to ask anybody in the first century where [food] came from, they would reply, "From plants, fish, and animals." They have grown or caught this food themselves. So anybody in the first century knows that you live because the chicken died. . . . All of this organic material that we feed ourselves with—which we must have or we die—has given its life for us in substitution. . . .
Either you die or something else living dies so that you may live. Jesus picks up on that language and says, "Unless you eat my flesh, you will die. I die so that you may live."1Jesus used a principle known experientially by anyone who hunted, fished, farmed, or gathered to teach about himself and his mission. He is bread from heaven, dying so we can live, just as the food we eat has died so we can live. He was speaking prophetically of his death—the task he came to accomplish—when he said "I am the bread of life . . . If anyone eats of this bread, he will live forever."
But he is so much better than the physical food that sustains our physical life. The life he gives is eternal. And we eat of his flesh by trusting in him (John 6:47), especially in his death for us.
1The God Who Is There by D. A. Carson, page 145.