Henry F. May, Professor of History at Berkeley, has spent ten years trying "to find the 18th-century roots of 19th-century American culture" because there is no comprehensive book on the subject. As he looks back beyond the 19th-century compromise between "progress" and "moral certainties" he discovers not one Enlightenment but four. The first and most important (1688-1787) was Moderate, dominated by the rational Calvinism of most of the Founding Fathers, who desired "a delicate balance" between extremes in thought, politics, and society. The second (1750-1789) was more Skeptical, associated with Benjamin Franklin and those who ridiculed the pieties of religion and doubted the efficacy of reason. The third (1776-1800) arose from the Revolutionary dogmatism of Tom Paine and others who transformed the pursuit of "secularity and modernity" into an intolerant quest for utopia. This last provoked an anti-intellectual reaction which discredited all three enlightened movements and introduced a fourth: the Didactic Enlightenment (1800-1815), dedicated to the practical, intuitive morality of the Scottish philosophy of Common Sense. Although May confines the Enlightenment(s) to those who relied on the "natural faculties" rather than "revelation, tradition, or illumination," he maintains that outright irreligion had little influence in America, despite the introduction of irreligious writings from Europe, and this facilitated the 19th-century compromise. Unfortunately, May's typology of ideas ignores the psychology of cultural change and suffers from listless prose and lame generalizations (e.g., "My story ends with the defeat or perhaps the assimilation of the Enlightenment" - well, which?). At the end, the reader will know the 18th century, but he will share May's uncertainty as to exactly how the 19th-century culture grew from it. (Kirkus Reviews)