In a morbid condition of the brain, dreams often have a singular actuality, vividness and extraordinary semblance of reality. At times monstrous images are created, but the setting and the whole picture are so truthlike and filled with details so delicate, so unexpected, but so artistically consistent, that the dreamer, were he an artist like Pushkin or Turgenev even, could never have invented them in the waking state. Such sick dreams always remain long in the memory and make a powerful impression on the overwrought and deranged nervous system.
–Dostoevsky, Crime and Punishment, Ch 5
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