The Light and Dark

Everyone always said that there is a side of the light and a side of the dark. But why is darkness always portrayed as bad, or evil? And why is light always considered to be hope, kindness and all that is good in the world? Two completely opposite worlds, worlds of light and dark, are about to collide. What will happen when they do? Will it be destruction? Death? Or will it be creation? Life? Only time will decide our fate...