This book had its beginning ten years ago in a series of brief discussions supplementing a text used in the class-room. Their purpose was to amend certain theoretical views even then generally questioned by economists, and to present most recent opinions on some other questions. These critical comments evolved into a course of lectures following an original outline, and were at length reduced to manuscript in the form of a stenographic report made from day to day in the class-room. The propositions printed in italics were dictated to the class, to give the key-note to the main divisions of the argument. Repeated revisions have shortened the text, cut out many digressions and illustrations, and remedied many of the faults both of thought and of expression; but no effort has been made to conceal or alter the original and essential character of the simple, informal, class-room talks by teacher to student. To this origin are traceable many conversational phrases and local illustrations, and the occasional use of the personal form of address. The lectures, at the outset, sought to give merely a summary of widely accepted economic theory, not to offer any contribution to the subject. While they were in progress, however, special studies in the evolution of the economic concepts were pursued, and the manuscript of a book on that more special subject was carried well toward completion. That work, which it is hoped some time to complete, was, for several reasons, put aside while the present text was preparing for publication. The economic theories of the present transition period show many discordant elements, yet the author felt that his attempt to unify the statement of principles, in an elementary text explaining modern problems, and consistent in its various parts, helped to reveal to him both difficulties and possible solutions in the more special theoretical field. The unforeseen outcome of these varied studies is an elementary text embodying a new conception of the theory of distribution, an outline of which will be found in Chapter Forty-three. It is, in brief, a consistently subjective analysis of the relations of goods to wants, in place of the admixture of objective and subjective distinctions found in the traditional conceptions of rent, interest, and price.