The product of 20 years' labor, this work contains a wealth of fascinating material charting the manifold ways in which Americans have understood the rise, fall, and occasional renovation of American power. The author, who teaches history at New York University, investigates a wide range of sources in unfolding his subject, and he is alive to discoveries that challenge preconceived notions: thus we find Theodore Roosevelt, in 1910, ridiculing the importance he had placed on race as a half-baked and comic extravagance of his youth, and Charles Beard disparaging the importance of the material factor in history. But the work, conceived as a study of "myth," is not without its weaknesses. The larger tensions White erects to make sense of his subject -- the contrast, for instance, between realism and idealism, or between "The American Century" (Henry Luce) and "The Century of the Common Man" (Henry Wallace) -- do not by any means cover the ground, or are themselves shot through with ambiguity. The result is a disjunction between mass and meaning, or trees and forest, that the author does not surmount. Anyone interested in the problem of rise and decline or that of changing American conceptions of their role in the world will find many rewards in this book, but the end result is more a restatement of the problem than an explanation of the phenomenon.