What would your good do if evil didn’t exist, and what would the earth look like if all the shadows disappeared? After all, shadows are cast by things and people. Here is the shadow of my sword. But shadows also come from trees and from living beings. Do you want to strip the earth of all trees and living beings just because of your fantasy of enjoying the naked light?
Mikhail Bulgakov, The Master and Margarita, Chapter 29 (trans. Michael Glenny)