There is so much darkness in Ember, Lina. It's not just outside, it's inside us, too. Everyone has some darkness inside. It's like a hungry creature. It wants and wants and wants with a terrible power. And the more you give it, the bigger and hungrier it gets.
Jeanne DuPrau (2012). “The Books of Ember Omnibus”, p.96, Random House Books for Young Readers