When Don DeLillo chose Hitler Studies as the field of a small-college professor in his absurd, funny 1985 novel White Noise, it was a fair barometer of just how far Hitler's obsessive explainers had been pushed to the fringes of academia; his elusive persona has slipped ever further into abstraction. In his rigorous and indispensable Explaining Hitler, Ron Rosenbaum takes a step back and surveys a vast disparity of theoretical Hitlers that "might not recognize each other well enough to say 'Heil' if they came face to face in hell." There's Hitler as true believer (Alan Bullock); as actor convinced of his own act (Hugh Trevor-Roper); as frequently indecisive and Hamlet-like (Christopher Browning); as horribly decisive about the Final Solution from the beginning (Lucy Dawidowitz), and as beyond explanation altogether (Claude Lanzmann). An obsessive in his own right, Rosenbaum investigates the uncertain roots of Hitler's anti-Semitism, his alleged sexual dysfunction, his specific role in the Final Solution, and other issues through pointed interviews and illuminating archival discoveries. More often than not, he finds that the explainers wind up saying more about their own agendas than they say about Hitler. Foremost a journalist, Rosenbaum tends to gravitate toward the most sensible and well-supported interpretations. He reserves a special admiration for the brave writers of The Munich Post, a left-wing newspaper that continued to dog Hitler during his rise to power, sometimes at the expense of their lives. Explaining Hitler is above all a plea for the return of common sense in coming to terms with the most evil and enigmatic figure of the 20th century.