A cursory ex'amination of the contents of this book will probably give the impression that the theoretical aspects of the science receive in it greater emphasis than present opinion among economics teachers can approve. The writer may be permitted to urge, in his own defense, that the method which he has employed was chosen not without careful consideration of the existing situation in the field of economics instruction. In the present stage of university evolution, economics is almost everywhere taught by men who have been trained in the science; a text-book writer is therefore justified in relying upon the teacher for the supplying of many of the concrete facts which in a given situation are most effective for purposes of instruction. An efficient teacher can base a highly practical course upon a text-book which is fundamentally theoretical. Moreover, in most colleges and universities the general course in economics is usually followed by special courses, and these, in order to attract any considerable number of students, must be practical. It is not too much to say that, for a majority of students, theoretical study begins and ends with the introductory course. Such a course ought, therefore, to present a reasonably thorough study of the general principles Of the science.