This volume is the first of a series of studies in which I hope to discuss in various aspects the theory of the State. Its starting point is the belief that in such a theory, the problem of sovereignty is fundamental, and that only in the light of its conception can any satisfactory attitude be adopted. It is essentially a critical work, and it is only in the most tentative fashion that I have hinted at what seems to me the right avenue of approach. When I have finished similar studies in the political theory of the Catholic Reaction in France during the nineteenth century, and of the Conciliar Movement in the fifteenth, it may be that I shall be able to attempt a more constructive discussion. But it has not seemed to me entirely purposeless to point out the dangers of an attitude fraught with consequences so momentous to the character of our political institutions. How much it owes to Maitland and Saleilles and Dr. Figgis, I dare not estimate but if it sends anyone to their books and particularly to Maitlands I shall be well content. I owe much, too, to the work of my friend and colleague, Professor Mcllwain, from whose High Court of Parliament I have derived a whole fund of valuable ideas. Nor have I, as I hope, failed to learn the lesson to be learned from the constitutional opinions with which Mr. Justice Holmes has enriched this generation. I would add that it was from Mr. Fisher that I first learned to understand the value of individuality, as it was from Mr. Barker that I first learned the meaning of community. I should like, too, to associate whatever there is of good in the thought of this book, with the name of my friend, Alec Rowan Herron, Scholar of New College and secondlieutenant in the Kings Eoyal Rifles, who fell at Grivenchy in the first year of war. What we have lost in Trim only those of us who had the rare privilege of his intimate friendship can tell but I may be permitted to say that it was the opinion of those with the right to judge that a very brilliant career lay before him. This book could never have been written were it not for the constant and splendid sympathy of my friend, Professor Frankfurter of the Harvard Law School. If I mention that, and the debt it of course owes to my wife, it is not in repayment, but in recognition. They, I know, will understand. I have to thank the editors of the American Political Science Review, the Canadian Law Times, the New Republic, and the Journal of PMlosophy, Psychology and Scientific Methods for leave to use material already printed in their pages. JEL. J. L. September 28, 1916.