But it may be said that effective acting depends, not on doubt, but rather on belief, on confidence or "credit." This will prove to be true, excepting in what it denies. To be commonplace, to write down here and now what is at once the truism and the paradox of this book, a vital, practical belief must always live by doubting. Was it Schopenhauer who declared that man walks only by saving himself at every step from a fall? The meaning of this book is much the same, although no pessimism is either intended or necessarily implied in such a declaration. Doubt is no mere negative of belief; rather it is a very vital part of belief, it has a place in the believer's experience and volition; the doubters in society, be they trained at the University or not, and those practical creatures in society who have kept the faith, who believe and who do, are naturally and deeply in sympathy. And this essay seeks to deepen their natural sympathy. Here, then, is my simple thesis. Doubt is essential to real belief. Perhaps this means that all vital problems are bound in a real life to be perennial, and certainly it cannot mean that in its support I may be expected by my readers to give a solution of every special problem that might be raised, an answer to every question about knowledge or morality, about religion or politics or industry, that might be asked. Problems and questions, of course the natural children, not of doubt, but of doubt and belief, may be as worthy and as practical as solutions. Some of them may be even better put than answered. But be this as it may, the present essay must be taken for what it is, not for something else. It is, then, for reasons not less practical than theoretical, an attempt to face and, so far as may be, to solve the very general problem of doubt itself, or say simply--if this be simple--the problem of whatever in general is problematic; and, this done, to suggest what may be the right attitude for doubters and believers towards each other and towards life and the world which is life's natural sphere; emphatically it is not the announcement of a programme for life in any of its departments. The substance of chapters I., II., III., IV., and V. in small parts, and VI. and VIII. was given during the summer of 1903 in lectures before the Glenmore School of the Culture Sciences at Hurricane in the Adirondacks, and except for some revision chapters V. and VII. have already been published--Science, July 5, 1902, and the journal of Philosophy, Psychology and Scientific Methods, June, 1905. To Professor Muirhead, the Editor of the Ethical Library, I wish here to express my hearty appreciation of his interest and assistance in the final preparation of this volume for publication. A. H. L. THE UNIVERSITY OF MICHIGAN, ANN ARBOR, MICHIGAN, U.S.A. CONTENTS.