When, in the summer of 1951, I was in a position to embark on research for a Ph.D. thesis, I found myself unable to decide on a suitable subject. It was Professor Knowles who suggested Matthew Paris to me, and who supervised my researches during the ensuing three years. The result was a study of the relationship and chronology of Matthew Paris's historical manuscripts which is incorporated--much altered, and, as I hope, improved--in the present work. My especial thanks are due to Professor Knowles, who, besides helping me as a supervisor and afterwards, has read the whole of this book in typescript and been kind enough to accept it for publication in the series of medieval studies which he edits. I must also thank Professor Galbraith, who has taken a lively interest in my work, and thereby been a constant source of encouragement and stimulation. Professor Cheney has provided help of a rather different kind, for which I must also record my thanks: he has read this book in typescript and proof and saved me from numerous errors, as well as making many suggestions which led to some important alterations in the text. For his encouragement since my undergraduate days, frequent loans and gifts of books, and much learned assistance, I must thank Professor Dickins. I would also like to thank Dr R. W. Hunt of the Bodleian Library, Dr C. E. Wright and Mrs Antonia Gransden of the British Museum, and Mr H. L. Pink of the University Library, Cambridge, for their help concerning manuscripts; Mr A. G. Woodhead for helping me with Matthew's Latin, and Dr M. H. Tweedy for helping me with his French; Dr T. E. Faber for advising me on some points concerning Matthew's scientific interests; and Professor Mynors, Dr Dorothy Whitelock, and Mr H. M. Adams. It is not perhaps inapposite here for me to record my obligations and thanks to my colleagues of Corpus Christi College for enabling me to complete this study by electing me into their Fellowship; and to my wife for her patience and forbearance during the many hours I have had to spend engrossed in Matthew Paris.