He said to them, "Come, and see." They came and saw where he was staying, and they stayed with him that day. It was about the tenth hour.{4:00 PM.}

 So what John is saying is that Jesus is the real light come to illumine men. Before Jesus came there were other lights which men followed. Some were flickers of the truth; some were faint glimpses of reality; some were will o' the wisps which men followed and which led them out into the dark and left them there. It is still the case. There are still the partial lights; and there are still the false lights; and men still follow them. Jesus is the only genuine light, the real light to guide men on their way. 