The theory of value set forth in Chapter I, and presupposed in the positive argument of the book, is that first set forth in an earlier book by the present writer, _Social Value_, published in 1911. That book grew out of earlier studies in the theory of money, in the course of which the writer reached the conclusion that the problem of money could not be solved until an adequate general theory of value should be developed. The present book thus represents investigations which run through a good many years, and to which the major part of the past six years has been given. On the basis of this general theory of value, and a dynamic theory of money and exchange, our positive conclusions regarding the value of money are reached. On the same basis, a psychological theory of credit is developed, in which the laws of credit are assimilated to the general laws of value. In a final section, the constructive theory of the book is made the basis for a "reconciliation" of "statics" and "dynamics" in economic theory--an effort to bring together the abstract theory of price (_i. e._, "statics") which has hitherto chiefly busied economists, and the more realistic studies of economic change (_i. e._ "dynamics") to which a smaller number of economists have given their attention. These two bodies of doctrine have hitherto had little connection, and the science of economics has suffered as a consequence. This book was not written with the college student primarily in mind. None the less, I incline to the view that the book, with the exception of the chapter on "Marginal Utility," is suitable for use as a text with juniors and seniors in money and banking, if supplemented by some general descriptive and historical book on the subject, and that the whole book may very well be used with such students in advanced courses in economic theory. I think that bankers, brokers, and other business men who are interested in the general problems of money, trade, speculation and credit, will find the book of use. Naturally, however, it is my hope that the special student of money and banking, and the special student of economic theory will find the book of interest. The book may interest also certain students of philosophy and sociology, who are concerned with the applications of philosophy and social philosophy to concrete problems.