Two Realms

Genesis 1: 4

And God saw the light, that it was good; and God divided the light from the darkness.

Here in verse four our attention is turned toward the visible spectrum.  Can anyone argue that visible light is not good?  What is more God has purposefully created a universe in which the light is divided from the darkness, so that two realms emerge.  What?  Light has to be separate from darkness; you say.  Perhaps.  Perhaps in this universe that is so, but it is so because God made it so.