The classic image of the American nation - a melting pot in which differences of race, wealth, religion, and nationality are submerged in democracy - is being replaced by an orthodoxy that celebrates difference and abandons assimilation. While this upsurge in ethnic awareness has had many healthy consequences in a nation shamed by a history of prejudice, the cult of ethnicity, if pressed too far, threatens to fragment American society to a dangerous degree. Two-time Pulitzer Prize winner in history and adviser to the Kennedy and other administrations, Arthur M. Schlesinger, Jr., is uniquely positioned to wave the caution flag in the race to a politics