Verse 31 I knew him not; that is, as the Messiah. It is evident, from Matthew 3:14,15, that Jesus was personally known to John when he came to be baptized; as, in fact, considering the relation subsisting between their mothers, arising out of the circumstances related by Luke, (Luke 1:1-2:52) must almost necessarily have been the case. He knew him, however, only as a devout and holy man, until after the baptismal ceremony was performed; when it was revealed to him that he was the Messiah, in the manner specified in the John 1:32,33.--But that, &c. The meaning is, that he knew only that the Messiah was about to appear.