[10] Davenport, "Seligman, 'Social Value,'" _Journal of Pol. Econ._, 1906; _Value and Distribution_, Chicago, 1908. This last work reproduces, in abridged form, the article on Professor Seligman, in a footnote, pp. 444 _et seq._ Schumpeter, "On the Concept of Social Value," _Q. J. E._, Feb., 1909; "Die neuere Wirtschaftslehre in den Vereinigten Staaten," _Jahrbuch fuer Gesetzgebung, Verwaltung und Volkswirtechaft im Deutschen Reich_, 1910, pp. 913 _et seq._ In the last-named article (p. 925, n.) Professor Schumpeter indicates that his objection to the social value concept relates not so much to the question of fact as to the question of method. The English article in the _Quarterly Journal_ contains Schumpeter's fullest treatment of the topic. [11] Boehm-Bawerk, "Grundzuege der Theorie des wirtschaftlichen Gueterwerts," Conrad's _Jahrbuecher_, N. F., Bd. XIII, 1886, p. 478. [12] _Natural Value_, p. 52, n. [13] Sax, Emil, _Grundlegung Der Theoretischen Staatswirtschaft_, Vienna, 1887, p. 249. [14] See _supra_, p. 3, note 1. PART II CRITIQUE OF CURRENT VALUE THEORY CHAPTER II FORMAL AND LOGICAL ASPECTS OF THE VALUE CONCEPT The study of wealth is meaningless, unless there be a unit for measuring it. The questions to be answered are quantitative.... Reciprocal comparisons give no sums.... Ratios of exchange alone afford us no answer to the economist's chief inquiries.[15] This quotation from Professor Clark raises an issue which we must examine in detail. Professor Clark proceeds, pointing out the need for a homogeneous element, among the diversities of the physical forms of goods, capable of absolute measurement, if goods are ever to be added together, or a sum of wealth obtained. Money, on the surface of things, affords this common standard, but "the thought of men runs forward to the power that resides in the coins." This power is effective social utility, the quantitative measure of which is value. Elsewhere in his writings,[16] Professor Clark insists on the conception of value as a quantity, an absolute magnitude, and he consistently makes use of this conception. All of the exponents of the social value concept named, except Professor Seligman, follow him in this, and it may be considered an essential feature of the theory. Marginal utility is a definite quantity, social marginal utility is a definite quantity, and value, if conceived as identical with social marginal utility, or as the quantitative measure of it (the difference is verbal, for present purposes, at least), must be so considered. A _ratio of exchange_, then, is a ratio between two quantities of social marginal utility, or social value, rather than between two physical objects, and _price_, in this view, is a particular sort of ratio of exchange, namely, one where one of the terms of the ratio is the social marginal utility, or the social value, of the money unit.