I offer my thanks to several friends who have been kind enough to read the proofs of this book, and to send me corrections and suggestions; among whom I will mention Professors John Adams and J.H. Muirhead, Dr. A. Wolf, and Messrs. W.H. Winch, Sidney Webb, L. Pearsall Smith, and A.E. Zimmern. It is, for their sake, rather more necessary than usual for me to add that some statements still remain in the text which one or more of them would have desired to see omitted or differently expressed.

I have attempted in the footnotes to indicate those writers whose books I have used. But I should like to record here my special obligation to Professor William James's Principles of Psychology, which gave me, a good many years ago, the conscious desire to think psychologically about my work as politician and teacher.

I have been sometimes asked to recommend a list of books on the psychology of politics. I believe that at the present stage of the science, a politician will gain more from reading, in the light of his own experience, those treatises on psychology which have been written without special reference to politics, than by beginning with the literature of applied political psychology. But readers who are not politicians will find particular points dealt with in the works of the late Monsieur G. Tarde, especially L'Opinion et la Foule and Les Lois de l'Imitation and in the books quoted in the course of an interesting article on 'Herd Instinct,' by Mr. W. Trotter in the Sociological Review for July 1908. The political psychology of the poorer inhabitants of a great city is considered from an individual and fascinating point of view by Miss Jane Addams (of Chicago) in her Democracy and Social Ethics.

GRAHAM WALLAS.