My first acknowledgement must be to the Society of Antiquaries of Scotland, who did me the honour of choosing me as Rhind Lecturer for the year 1931. From individual members of that Society, and from the officials at the National Library of Scotland, at the Register House, and at His Majesty's Office of Works, I have received kindness and help at every point. To the last-named Office I am indebted for permission to reproduce more than one of my illustrations. My footnotes will mark my indebtedness to Dr James Curie for details about Melrose, and to Professor R. K. Hannay, Historiographer Royal, for advance proofs of his Ada Dominici Concilii and for much valuable information. Finally, Miss Jessie Cameron has generously supplied me with notes and transcripts from her as yet unpublished gleanings in the Vatican Archives.

The present volume contains more than twice the matter for which it was possible to find room in the actual lectures; but those lectures dictated its general form, and it seemed inadvisable to obliterate all traces of oral delivery. I have tried to leave no really important avenue altogether unexplored; but I am fully conscious that this volume, in many directions, can only indicate the problems which need much fuller investigation before the evidence can be looked upon as exhausted.