He brought him to Jesus. Jesus looked at him, and said, "You are Simon the son of Jonah. You shall be called Cephas" (which is by interpretation, Peter).

 John says that he did not know Jesus. Now John was a relation of Jesus ( Luke 1:36), and he must have been acquainted with him. What John is saying is not that he did not know who Jesus was, but that he did not know what Jesus was. It had suddenly been revealed to him that Jesus was none other than the Son of God. 