Imagine two adjacent rooms.  One is illuminated by a bright light.  The other is in darkness.

Open the door between the two rooms.  What happens?

Does the darkness invade the lighted room?  No.  Quite the opposite: the light pushes back the darkness.

Such is the fundamental truth of Epiphany.  As John 1:5 puts it, "The light shines in the darkness, and the darkness did not overcome it."