I have been thinking about medieval letters for over ten years. This book is a partial harvest of those labours. It is far from everything that could be said about letters, and probably not the last word I will have to say about them, either. There is so much to say about letters that it took me a long time to find a way to say something about them. This is not the book I thought I was writing when I began, and it probably bears only passing resemblance to the book that was originally contracted (sorry, Caroline). But, in the end, it gradually became the book I wanted to write. I hope that it will enable medieval royal letters to be viewed in a new way.