This scene is very important in the Gospel of Mark. Jesus never asked what people thought about him. Now he does. He must teach the disciples to understand him better and especially to understand what type of Messiah he is and what type of disciples they are supposed to be. He is a Messiah who will suffer death but who will rise and they, his disciples, will have to follow the way of the cross too. As the blind man who learned to see only gradually so they too will only slowly come to understand who Jesus is.