Enthusiasm, in the religious sense, is more akin to fanaticism than fervor. As Monsignor Ronald Knox describes, it is that recurring situation in Church history in which men and women, seek to be less and less "of the world" and more and more attentive to the guidance of the Holy Spirit. Their assumption is audacious yet simple: grace does not perfect nature; it destroys and replaces it. The inevitable result: separation, secession, schism. In twenty-three informative and entertaining chapters, Knox presents various enthusiastic movements: the first-century Corinthians, Montanists, Donatists, Albigenses, the Reformation sects, Jansenists, Quietists, Convulsionaries, Quakers, and Methodists-with special reference to those episodes from the seventeenth and eighteenth centuries. Under Knox's perceptive pen, religious history is interpreted as com-pelling drama, in which fascinating characters-like St. Paul and Tertullian; Martin Luther and the French Prophets; Madame Guyon and J.-B. Bossuet; Blaise Pascal and François Fénelon; George Fox and John Wesley; and many others-grapple and quarrel as much with themselves and their fellow Christians as with God himself.

First published in 1950, the fruit of thirty years of research and writing, Enthusiasm is "The Book" in Knox's impressive bibliography-the whole of his literary life, he said. In subject and style, it makes for a fitting masterpiece: a survey of centuries of religious achievement which meets squarely the undeniable truth that "men will not live without vision"-a meeting haunted by these strange words: "the only vice is inertia and the only virtue, enthusiasm."