This book is concerned with religious revivalism in the United States since 1825. It attempts to explain the part which revivalism has played, and is playing today, in the social, intellectual, and religious life of America. The aim has been, in describing the development of modern revivalism and the men who devoted their lives to it, to look below the surface phenomenon in an effort to discover why revivals have constantly recurred, what their effects have been, and what they meant not only to those directly concerned but to all Americans. If the revivals of the past century and a quarter have not always been the crucial factors in the course of American history that their devout exponents claimed, they have nevertheless been more significant than the social historians have yet acknowledged. from the Preface