It is not my purpose to present a complete system of economics, based upon subjective phenomena. Much of the work leading to that end has been too well done to need a repetition. I Shall, however, use my studies to furnish fresh illustrations of the importance of such a system, and of the possibility of applying its principles to other fields than those in which they are already in use.* I am interested in the problems of the consumption of wealth, and have tried to develop a theory of this subject. My main endeavor will be to Show that the theory of consumption furnishes a better basis for the theories of value and of distribution than the accepted theory of cost of production. If this change is made the theory of production becomes independent of the theory of distribution, and can be presented in a way more capable of showing the causes of progress and prosperity. An especial emphasis will also be given to the causes deter mining the standard of life. It will, however, be necessary to direct attention, first of all, to the history of economic theory, Since many of the dificulties in the reconstruction of these theories lie in the interpretation of their history.