" Evolutionary speaking, the practice of taking revenge has shown itself to be so effective that only the most vengeful of us have survived. Vengeance or death. It sounds like the title of a western, right, but remember it was the logic of retaliation that created the constitutional state. The enshrined promise of an eye for an eye, the sinner burning in hell or at least dangling from the gallows. Revenge is basically the foundation of civilisation. "
― Jo Nesbø , Nemesis (Harry Hole, #4)