[18] Some of my socialist friends object to the interpretation of Marx given above. I feel strengthened in my position here by finding the same view expressed by Conrad in his _Grundriss_, etc., 4te Aufl, Bd. I, pp. 17-18. Professor O. D. Skelton's admirable _Socialism_ (Hart, Schaffner & Marx Series, 1911) comes to hand while the proof sheets of the present volume are being revised. _Cf._ his interesting chapter on the Marxian theory of value. [19] Seligman, _Principles_, pp. 184-85. See also Taylor, W. G. L., "Values, Positive and Relative," _Annals A. A._, vol. IX, pp. 70-106. Taylor, who follows Professor Clark largely, accepts the conception of social value as a quantity. [20] Marx, _Capital and Capitalistic Production_, London, 1896, pp. 2-4. George, _Science of Political Economy_, New York, 1898, chap. XI. [21] _Natural Value_, p. 53, n. [22] "The Concept of an Economic Quantity," _Q. J. E._, May, 1907. Professor Carver insists on the quantitative nature of value, taking as his point of departure the point made _infra_, p. 27, with reference to money as a measure of values. But it is not clear that he has entirely freed himself from the conception of relativity, for he continues to speak of value as "purchasing power" (pp. 438-39), and this term has usually the relative, rather than the absolute, significance. _Cf._ his use of the term "purchasing power" in his _Distribution of Wealth_, 1904, pp. 51-52, where the _relativity_ of value is insisted on as a basis for a criticism of Professor Clark's amendment of the Austrian theory. [23] Paris, 1902, vol. I, p. 63.