Charles Spurgeon Commentary John 1:7-9

"The same came for witness, that he might bear witness of the light, that all might believe through him. He was not the light, but [came] that he might bear witness of the light. There was the true light, [even the light] which lighteth every man, coming into the world." — John 1:7-9 (ASV)

The same came for a witness, to bear witness of the Light, that all men through him might believe. He was not that Light, but was sent to bear witness of that Light. That was the true Light, which lighteth every man that cometh into the world.

That John could not do; he could only bear witness to Christ, the true Light, who alone is able to illuminate, in a larger or lesser degree, every man that cometh into the world.