The intellectual history of race, one of the most pernicious and enduring ideas in American history, has remained segregated into studies of black or white traditions. Bruce Dain breaks this separatist pattern with an integrated account of the emergence of modern racial consciousness in the United States from the Revolution to the Civil War. A Hideous Monster of the Mind reveals that ideas on race crossed racial boundaries in a process that produced not only well-known theories of biological racism but also countertheories that were early expressions of cultural relativism, cultural pluralism...