He was not that Light, but was sent to bear witness of that Light.
The wind blows to the south and turns to the north; round and round it goes, ever returning on its course.Ecclesiastes 1:6 NIV
That was the true Light, which lighteth every man that cometh into the world.John 1:9 KJV
The same came for a witness, to bear witness of the Light, that all men through him might believe.John 1:7 KJV