We must admit that it is extremely difficult to formulate a theory sufficiently general to encompass all possible sufficient causes of wars. With regard to necessary causes, however,... it is weapons. Without weapons wars could not be fought. We are told that, deprived of weapons, people would still fight with sticks and stones. This, however, need not concern us. We are concerned not just with fighting but with the sort of mass insanity that can destroy the entire civilization, the product of millenia of accumulated effort, in a matter of hours. And this can be done only with real, up-to-date weapons, not sticks and stones.