Thoughts: After the exile in Babylon the Torah became known as the Bread of Life. In the Torah we read: "One does not live by bread alone, but on every word that comes from the mouth of the Lord (Deuteronomy 8.3). Here Jesus is showing himself as the fulfillment of that statement/prophetic word. But alas, we have miscommunication as the crowd cannot see Jesus as the "Word" but only as the "feedbag" that has filled their bellies. Jesus here is proclaiming himself as the source of all life.
Question: They ask: "what sign will you perform?" What a crazy question, for Jesus has just performed the feeding of the 5,000. But you see we are never satisfied with yesterdays sign...we want one today. Have you ever experienced a miracle? Do you think God still works "signs" and "wonders" today?