In the middle of the Garden of Eden were two trees; the tree of life and the tree of the knowledge of good and evil. God gave names to these two trees to reveal to Adam what would be his should he eat their fruit. Eat the fruit of the tree of life and eternal life was his. Eat the fruit of the tree of the knowledge of good and evil and the knowledge of good and evil was his. By naming the trees, God formed the first sacrament, attaching his word, his promises, by naming the plain fruit of the trees.
Since the fall, God has barred our way to the tree of life. Eternal life by that means is beyond the reach of humans.
Yet God has instituted a new sacrament by naming another object. That object is his Son, who is called "the bread of life." Just as the name of the tree of life told Adam of the promise of eternal life, so the name "bread of life" tells us of God's renewed promise of eternal life through feeding on his Son by faith.
Jesus said "I tell you the truth, he who believes has everlasting life." But, how can we demonstrate that we believe? Jesus continued, "here is the bread that comes down from heaven, which a man may eat and not die. I am the living bread that came down from heaven. If anyone eats of this bread, he shall live forever." It is not the bread itself set before us this morning which gives eternal life, this is just bread. But Jesus is the bread of life and he gives this bread to us and calls it his body. As we eat what he has called his body, we demonstrate our faith in his promise of eternal life for all who believe in him.