We are making our way through the sixth chapter of the Gospel of John, sometimes referred to as the "Bread of Life Discourse." Today Jesus hears the people around him "murmuring" about him and his teaching. This recalls the attitude that our ancestors had toward Moses and the teachings that he revealed to them from God. 'Murmuring' in the Bible goes beyond incredulity -- the people weren't simply in awe of what he was saying; it shows that they doubted and disagreed with what was being taught. Jesus's answer to them is that it is God the Father who draws them and teaches them the Truth, if only the people will allow it.
The Eucharist is the Living Bread come down from heaven. It is Jesus' flesh, for the life of the world.