When Jesus decided to change Peter's name in John 1:42, it demonstrated how Jesus looks at men. He does not only see what a man is; he also sees what a man can become. He sees not only the actualities in a man; he also sees the possibilities. Jesus looked at Peter and saw in him not only a Galilean fisherman but one who had it in him to become the rock on which his church would be built. Jesus sees us not only as we are, but as we can be; and he says: "Give your life to me, and I will make you what you have it in you to be." Once someone came upon Michelangelo chipping away with his chisel at a huge shapeless piece of rock. He asked the sculptor what he was doing. "I am releasing the angel imprisoned in this marble" he answered. Jesus is the one who sees and can release the hidden hero in every man.
From William Barclay's
Commentary on The Gospel of John