They said therefore to him: What sign therefore dost thou shew, that we may see, and may believe thee? What dost thou work? Our fathers did eat manna in the desert, as it is written: He gave them bread from heaven to eat.
Then Jesus said to them: Amen, amen I say to you; Moses gave you not bread from heaven, but my Father giveth you the true bread from heaven. For the bread of God is that which cometh down from heaven, and giveth life to the world. They said therefore unto him: Lord, give us always this bread. And Jesus said to them: I am the bread of life: he that cometh to me shall not hunger: and he that believeth in me shall never thirst.
John 6:30-35 (Douay-Rheims Bible)
Dear Father you have given us the greatest sign ever, you gave us your Son as the bread of life. There is no other sign needed. Jesus gave of himself totally. If we don't believe in him or the fact that he is the bread of life then we have nothing. We will hunger forever for the truth and our thirst will never be quenched. He showed us and gave us so much to believe in his presence in the Eucharist, the bread par excellence. How can we ask for a sign when he is constantly present, just as those who were with him were. They too were looking for signs when he was present with them. Yet we have many who believe, but only a few who come to claim that Jesus is the true Son of God, the bread of life. I had a personal encounter with the bread of life, that didn't give me my belief, but strengthened that belief even more. It wasn't a sign for me, he fed me and gave me what I have thristed for, his love.