Although perhaps the world's best known athlete, Cassius Clay is far more important as an American phenomenon of the 1960's than as a prizefighter. In his career as a boxer, he followed a traditional, even a stereotyped road to the top for a Negro, but his distortion of the American rags-to-riches story is peculiarly his own. When he defeated Sonny Liston for the world's heavyweight championship in 1964, he was hailed by press and public alike as...