One of the American Profiles designed to bring together ""the best biographical and interpretive writing on the lives of great Americans."" Consonant with Justin Kaplan's treatment in Mr. Clemens and Mark Twain (Pulitzer, NBA Awards, 1967), this collection of pieces by authorities and a contemporary (friend William Dean Howells) emphasizes the darker aspects of the life and art of the man known as the greatest American humorist. Dixon Wecter depicts him as ""a deeply conflicted, intermittent genius""; both Van Wyck Brooks and Bernard de Voto concentrate on his despair, while Dwight Macdonald makes ""an unsentimental journey"" and Leslie Fiedler traces Twain's artistic ""duplicity."" Selections on Twain's nom de plume, his muse, his disastrous flier on a typesetting machine and equally disastrous address to the august poets at an Atlantic dinner, on Huck and Jim and Hannibal (his ""predestined great good place"") round out the volume. Supplementary.