James Jamerson was the embodiment of the Motown spirit and groove- the invisible entity whose bass playing inspired thousands of imitators, and made it possible for anyone with a pulse to sit still whenever a Motown record was playing. Now for the first time in print, Jamerson's tumultuous life and musical brilliance are explored in depth through hundreds of interviews, forty nine transcribed musical scores, two hours of recorded all star performances, and more than fifty rarely seen photographs.