This book tries to describe the difference made to the papacy by the European Revolution of 1789 to 1815; or, in other words, what Catholicism was like before the deluge and what is was like after, what the continuity and what the differences.
Those who read the book will see that the point of view is sufficiently unusual in that it is not particularly French. English historians have normally seen the process through the eyes of the nearest Church to the English; and that has the merit, not only that the French was then the most numerous and prosperous Catholic Church in Christendom, but that France caused the revolution which overwhelmed the ancien régime not only in France itself but in all Europe. I have consciously avoided this point of view; not because I believe that there is little now to say on that matter (I believe the contrary) but because a volume on the vital French part in the process is already under preparation for this same series, by our expert in French Catholicism, Professor John McManners of Oxford.
I have consciously taken a viewpoint further south and further east; to try to see how it felt in Rome, or Naples, or Venice, or Innsbruck, or Freiburg im Breisgau, or Madrid, or Cadiz.
A part of the book started as the Prideaux lectures at the university of Exeter; another and overlapping part, as the Paddock lectures at the General Seminary in New York. To the trustees of those hospitable foundations I owe thanks.
In the Vatican archives I was helped by Monsignor Hermann Hoberg and Monsignor Charles Burns. At the archives of the Society of Jesus in Rome I received much kindness from Father Lamalle. The librarians at the Vatican library and the library of the Gregorian university, as well as the never-failing friends at the library of Cambridge university and the Bodleian library at Oxford, produced not only rare books but good advice.
In particular Lord Acton collected a mass of literature in order himself to write a book about this very theme. The book never got itself written; for Acton was not a writer of books but a man who sometimes hoped that he would be. He died nearly eighty years ago. But I could not have done this work without his frequent assistance.