"The inner censor of the mind of the true believer completes the work of the public censor; his self-discipline is as tyrannical as the obedience imposed by the regime; he terrorizes his own conscience into submission; he carries his private Iron Curtain inside his skull, to protect his illusions against the intrusion of reality."
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"I think most historians will agree that the part played by impulses of selfish, individual aggression in the holocausts of history was small; first and foremost, the slaughter was meant as an offering to the gods, to king and country, or the future happiness of mankind. The crimes of Caligula shrink to insignificance compared to the havoc wrought by Torquemada. The number of victims of robbers, highwaymen, rapists, gangsters and other criminals at any period of history is negligible compared to the massive numbers of those cheerfully slain in the name of the true religion, just policy, or correct ideology." 

- Arthur Koestler