Then Jesus said to them, "Very truly, I tell you, it was not Moses who gave you the bread from heaven. For the bread of God is that which comes down from heaven and gives life to the world." They said to him, "Sir, give us this bead always." Jesus said to them, "I am the bread of life. Whoever comes to me will never be hungry, and whoever believes in me will never be thirsty."
Our Old Testament reading included verses from Exodus 16, which told of the Israelites coming upon the "fine, flaky substance, as fine as frost on the ground."
In both stories, the first one that Jesus told and the older one of Moses and Aaron, the people of God appear to me to be humbled.
Bread from heaven is pretty nice, yet to gather it one must stoop, or sweep it up in one's arms while down on one's knees. God's provision, God's gift appeared after the layer of dew lifted on the surface of the wilderness.
In John's story, Jesus requires the people following him to move beyond the old, familiar symbol of manna from heaven, to believing that Jesus himself is the bread of life, given to satisfy their hunger and quench their thirst.
Jesus took their request for the bread of God and gave it back to them, repackaged. Responding to Jesus' instruction to come to him and believe in him requires great humility and imagination.