Justin Kaplan's biography begins when Samuel Clemens returned East at thirty-one in 1866, when he had already begun to make his mark as Mark Twain and the ""Hartford literary gentleman lived inside the sagebrush bohemian."" His theme is the dualism in Clemens' life: the humorist, man of the people in his writing, who panned The Gilded Age, yet who in his personal life opted for it, marrying wealth and taking on the obligations maintaining it entailed. Within this frame, the author fits a detailed accounting of Clemens' career as writer and lecturer, his ventures in publishing, and with the typesetting machine that took so much of his time and money, his speculations that led to bankruptcy and the long climb back, to a triumphant return to respectability and honor as a national eminence. The quality of his life with Livy and his children, particularly at the manor on Farmington Avenue, is communicated, as is the vehement fluctuation of his nature and the tenor of his relations with the major figures in his life, from his unfortunate brother Orion, (""Short of everything except advice from Sam"") to the revered Ulysses S. Grant. Perhaps ""communicated"" is too inclusive a word, for Mr. Kaplan's handling is always succinct, the better perhaps to pack it all in. His insights are sure, and the result is thorough, vigorous biography, muscular in tone but somewhat lacking in feeling.