Genesis 1:3-5
And God said, Let there be light: and there was light. And God saw the light, that it was good: and God divided the light from the darkness. And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
If God saw the light, that it was good, why didn’t he just keep it light?
If the ultimate goal is a heaven which is permanently full of light, where there is no day or night, then why did it get dark again?
The Naked Prophet 