There are resemblances and contrasts between the theory that is here presented and those of the Austrian economists, Karl Menger and Friedrich von Wieser; and one feature which distinguishes the present system from the others is a recognition of the difference between permanent capital, or an abiding fund of productive wealth, and particular capital-goods, or instruments of production, which perish in the using. The relation that this theory bears to the fascinating one recently published by Ex-minister von Böhm-Bawerk can best be made clear after a later volume on the dynamics of distinction shall have seen the light. If my present plan had admitted it, I should have been glad to cite and to discuss many specific contributions to the literature of the theory of distribution, such as those made by Professor Alfred Marshall, President Francis A. Walker, President Arthur T. Hadley, Professor Frank W. Taussig, Professor William Smart, Mr. John A. Hobson, Dr. Charles W. MacFarlane, Dr. Stuart Wood and Mr. Herbert M. Thompson. To three men I am indebted for general stimulus and suggestion, the effects of which must have appeared in any theoretical work that I have done. They are my teacher, the late Professor Karl Knies of Heidelberg, and my early associates in economic work, Professor Franklin H. Giddings of Columbia University and Professor Simon N. Patten of the University of Pennsylvania.