(d) Are the definitions and principles already logically educed from and applied to the great class of Valuables orderly arranged in "_a body_"? This is the only inquiry that remains, in order to determine whether Political Economy is already a "Science" in the strictest sense of that term. It is admitted, that a jumble of even just definitions and principles do not constitute a science, but only these when placed in a just order and interdependence. A "body" implies an organic arrangement of parts. It has been well said of the human body, that all its parts are reciprocally means and ends; the same may be said of every living organic body, whether vegetable or animal; and the same may be said in the way of analogy of every developed and recognized Science. All the definitions and propositions and illustrations in any science should be so arranged, as to show the mutual relations and reciprocal dependence of all the parts, and as to display the whole in harmony and symmetry. It is as certain as anything in the future can be in science, that new principles will be discovered in Economics as Time and Inquiry go on, and that these will find their place little by little in a fuller and more rounded "body" than is at present possible; while it is also as certain as anything in the future of science can be, that the Outline of economics is already perfectly drawn, that the great class of Valuables will never be enlarged nor be better described, that the category of Commodities, Services, Credits, is completed for all time, and that the analysis of each act of trade into two Desires and two Efforts and two Estimates and two Renderings and two Satisfactions will never yield additional elements. Political Economy is already a body of exact definitions and sound principles educed from and applied to a single class of facts. This body will indeed be enlarged by a future and finer scientific construction, the arrangement and interdependence of its parts will be better exhibited, the form and filling up of the Science within the outline already determined is sure to become more compact, more robust, and more beautiful, as the decades and centuries go by; while, as in the human body throughout all the changes of its growth and mature life, that future body of economic science in all its stages towards perfection will be but the continuation and fuller development of the present "body" of Political Economy. FOOTNOTES: [1] Green's Short History of the English People, p. 591. [2] See on this general topic, Mommsen's Provinces of the Roman Empire, _passim._ CHAPTER II. MATERIAL COMMODITIES.