Book excerpt: In 1954 Leon Festinger, a brilliant young experimental social psychologist in the process of outlining a new theory of human behavior - the theory of cognitive dissonance - and his colleagues infiltrated a cult who believed the end of the world was only months away. How would these people feel when their prophecy remained unfulfilled? Would they admit the error of their prediction, or would they readjust their reality to make sense of the new circumstances?