"Absolutely have to have dark in order to have light. [...] Gotta have opposites – dark and light, light and dark – continually in a painting. If you have light on light, you have nothing. If you have dark on dark, you basically have nothing. [...] You know, it's like in life: you've gotta have a little sadness once in a while, so you know when the good times come. I'm waiting on the good times now."
January 1, 1970
https://en.wikiquote.org/wiki/Darkness