This is he of whom I said, 'After me comes a man who is preferred before me, for he was before me.'

 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. 