‘My books are simply autobiographies,’ Mark Twain once confessed. True of most American writers, it seems especially true of a man who, as Ron Powers argues in this magisterial biography, ‘found a voice for his country’. Twain was haunted, Powers points out, by the notion of dual identity, ‘two selves inhabiting the same body’. He seemed constantly to be striving to reconcile those selves – and, in particular, struggling to forge a connection between his past and his present, his childhood as Samuel Langhorne Clemens, spent in ‘almost invisible’ townships in the American South, and his highly visible adulthood as Mark Twain, the most famous American author of his day. All of Twain’s best fictional work has to do with what Powers calls ‘the Hannibal decade’: his experiences as a child from 1843 to 1853 in the slaveholding state of Missouri. This was not simply a matter of nostalgia for the good old days before the Civil War. Nor was it merely a romantic idealisation of youth – although Twain did firmly believe that youth was ‘the only thing worth giving to the race’. He recognised that his boyhood years in the pre-Civil War South had formed him for good and ill, so to explore those years was to explore his own equivocal nature. And he also sensed that the differences he noted between his prewar and postwar selves were typical, representative. So to understand them was to begin to understand his nation, to take the measure of what he saw as an American version of the Fall.