I am very grateful to the Syndics of the Cambridge University Press for undertaking to publish a very substantial book on a very unfashionable subject. To meet their requirements the original draught has had to be cut very considerably, and, in particular, the critical apparatus, which amounted to some 35,000 words, has been drastically simplified. I hope that the basic support for scholarly readers will nevertheless remain adequate, and that some of what is lost may be made good by a bibliographical study of German Pietism which I have in hand.

Extended study abroad has been made possible by the financial generosity of the University of Durham, the British Academy, the British Council, the government of the former German Democratic Republic, the Deutscher Akademischer Austauschdienst, and the American Antiquarian Society, to all of whom I am deeply obliged. To many librarians and archivists at home and abroad I am indebted for assistance; perhaps I may mention especially the willingness of the Moravian archivists in Herrnhut and London to accommodate the inconvenient visits of a student with many other preoccupations.

My former colleagues in Durham extended their usual tolerance to my hobby-horses and Dr Anne Orde and Dr Jeremy Black gave special help. My wife has nobly endured a study of revival which has hardly granted the refreshing showers of grace envisaged by its promoters. To them all I am grateful.