There have been many studies of the idea of genius, but a signal virtue of this new account is its comprehensiveness. Rather than start in the 18th century, when the modern idea of genius emerged—as an exceptional quality located not in God but in man—or with the 19th-century Romantic poets' exaltation of genius as a kind of "divine fury," McMahon (history, Florida State Univ.; Happiness: A History) begins with the ancients, contrasting the Roman notion of ingenium with varied interpretations of genius in modern times. Crucial to the change in meaning of the term was "the waning of mimetic aesthetics," the idea that art was imitation rather than creation. Uniqueness and creativity became the hallmarks of genius from the 18th century on: "The man of genius has a way of seeing, of feeling, of thinking," wrote Diderot, "unique to him alone." McMahon concludes by examining the not always happy fate of the idea in our times. VERDICT This exceptional intellectual history is too densely written to appeal to the casual reader, but it's a gem of a book to be widely read by scholars in many fields, not just in the history of ideas.—David Keymer, Modesto, CA