Based on House of Leaves, Skinamarink, and personal experience. The dark isn't the absence of light. Light is the absence of dark. Let us not forget which one is natural, which one came first. We are all so lucky that the great ball of fire we revolve around won't extinguish within our lifespans, that we will hopefully never have to experience true darkness within our lifetimes. It is the true cosmic horror, an unknowable, unstoppable entity that surrounds us at all times and consumes everything it touches. Our unevolved brains rely so on light to make sense of the world, that without it our eyes would see things that aren't there, desperate for any sort of sight. Eternal darkness would drive any person to madness. The only thing worse are the things that live inside the darkness, the things that can actually hurt us.