The phenomenon of the self-conscious cultural icon and the character osmosis that so fascinated Klein in his studies of Americans were both in evidence in his portrait of Muhammad Ali né Cassius Clay. "Joining the young fighter Cassius Clay, Klein accurately captured both the frenzy and mounting controversy that would follow the fighter well after his legendary meeting with Sonny Liston. The result was Klein's first documentary feature, Cassius le Grand (1964-65). Years later, Klein returned to witness the now-seasoned champion face the awesome George Forman in Zaire. The re-edited result was the 1974 release Muhammad Ali, the Greatest, an incomparable portrait of an American legend" (Nancy Robinson, Walker Art Center).