What is it about the emptiness of night that appeals to evil, summons it?

Rémi used to tell me of a place he'd visited once, as a child, where the sun never fell, for months at a time, dousing the landscape in wretched light at all hours of the day. What a disconcerting place in which to commit evil! What horrors its inhabitants must have endured in their lifetimes, he would say, confined to committing their sins in the blazing brightness, flaws and edges and scars and blemishes all unflinchingly visible.

But God bless the dark night, that impenetrable shroud!