sentences:  That book related his search among contemporary historians for an adequate explanation for Hitler's evil—and the underlying tension between "exceptionalist" explanations (Hitler was off the grid of 'normal' human behavior) versus naturalist explanations (Hitler was at the end of, but within, a continuum of human behaviors).The work left Rosenbaum so drained and gloomy that the only antidote he could find was "to start walking around the city [New York] listening to Shakespeare tapes on a Walkman.