Whenever human beings have practiced cannibalism on some regular basis they have been moved to do so not by hunger but by an idea. In our own century there are likewise abundant examples of ethnic groups being obliterated or annihilated in holocausts perpetrated in the name of some idea. As put forward by the oppressors, the idea at issue claims some essential difference between oppressors and victims — although what is in fact always stressed are differences at the level of technological achievements.