It is a pleasure to record the various debts of gratitude I have incurred in writing this book. Ideal conditions for uninterrupted work and for stimulating discussion were provided by two institutions to whose far-sighted generosity many others are likewise indebted: the Humanities Research Centre of the Australian National University, which invited me to Canberra in 1978, and the Herzog August Bibliothek in Wolfenbüttel, which likewise made it possible for me to work in Germany in 1979. Without the facilities provided at both these centres the completion of this book would have taken immeasurably longer.

I also acknowledge my gratitude to the support received from the British Academy and its Small Grants Research Fund as well as to the Deutscher Akademischer Austauschdienst, both of whom made it possible to undertake working visits to a number of German libraries.

Two personal expressions of warm thanks are no less deeply felt for being the last to be mentioned. Peter Johnson of Cambridge has devoted much time to reading the manuscript and has given me the benefit of his own knowledge of Wolfram, not least when we were unable to reach agreement. Maria von Katte of Wolfenbüttel has likewise given up much of her time to discussion and to providing the stimulus which arises from the conviction of shared concerns.