There exists a subterranean world where pathological fantasies disguised as ideas are churned out by crooks and half-educated fanatics for the benefit of the ignorant and superstitious. There are times when this underworld emerges from the depths and suddenly fascinates, captures, and dominates multitudes of usually sane and responsible people, who thereupon take leave of sanity and responsibility. And it occasionally happens that this underworld becomes a political power and changes the course of history.
-- Norman Cohn, Warrant for Genocide: the Myth of the Jewish World-Conspiracy and the Protocols of the Elders of Zion