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Among Surrealist techniques exploiting the mystique of accident was a kind of collective collage of words or images called the cadavre exquis (exquisite corpse).
Based on an old parlor game, it was played by several people, each of whom would write a phrase on a sheet of paper, fold the paper to conceal part of it, and pass it on to the next player for his contribution.
The Surrealists used images rather than phrases to produce collages both accidental yet unified.
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