IT is extremely difficult to trace the formation of critical
ideas and impressions. Probably, therefore, I am even
deeper in debt than I realize. Where I was aware of a
debt I have tried to acknowledge it in the text; but besides
expressing my general gratitude to all, known and unknown,
whose good things I have used, I ought also to emphasize
how much, even when sometimes differing in conclusions,
I owe to the works of Professor Renwick, Professor Lewis,
and Dr. Spens. Only to the de Selincourt preface could one
owe more. I owe much also to the suggestions and criticism
on the part of the Clarendon Press itself, and I have to thank
the Cambridge University Library for the courtesy with
which I was allowed access to the books.

I wish very specially to express my gratitude to Miss
Helen Darbishire, without whose encouragement this book
would never have been begun at all, and to Professor
A. M. D. Hughes, without whose constant patience and wise
criticism it would never have been completed.

M. P. P.