'Every isolated passion is, in isolation, insane; sanity may be defined as a synthesis of insanities. Every dominant passion generates a dominant fear, the fear of its non-fulfilment. Every dominant fear generates a nightmare, sometimes in the form of explicit and concious fanaticism, sometimes in a paralysing timidity, sometimes in an unconscious or subconscious terror which finds expression only in dreams. The man who wishes to preserve sanity in a dangerous world should summon in his own mind a parlament of fears, in which each in turn is voted absurd by all the others.'

Bertrand Russell, Nightmares of Eminent Persons