What persuades men and women to mistake each other from time to time for gods or vermin is ideology. One can understand well enough how human beings may struggle and murder for good material reasons—reasons connected, for instance, with their physical survival. It is much harder to grasp how they may come to do so in the name of something as apparently abstract as ideas. Yet ideas are what men and women live by, and will occasionally die for.

Ideology, introduction (1991)