56 NATURE OF CAPITAL AND INCOME [Crar. IV land* and all natural agents under capital. Bohm-Bawerk,? while agreeing that it must be a product, insists that it must not apply to a finished product. Marx * denies that capital is productive. Bohm-Bawerk * admits that it is not ‘“‘independently’’ productive, but denies the Marxian corollary that it should not receive interest. Other writers make it codrdinate with land and labor as a productive element. As to what it is that capital produces there is further disagreement. Adam Smith ° affirms that capital produces “revenue,” Senior,’ that it produces “wealth.” Others vaguely imply that it produces value, services, or utility. Most of the definitions involve some reference to time, but in many different ways. Hermann 7 has in mind the time the wealth will last; Clark,® the permanency of the fund capital as contrasted with the transitoriness of its ! The fancied distinction between land and capital, viz., that the former yields rent and the latter interest, and that rent varies with different grades of land whereas interest is uniform for all sorts of capital, is based on a confusion between quantity and value of wealth. The return from land per acre will, it is true, vary according to the quality of the land. But so also the return from machinery of differ- ent grades will vary per machine. The return from different kinds of capital per $100 worth will, it is true, be uniform; but so will the return from land per $100 worth. For a full treatment of this confu- sion see Fetter’s “ The Relations between Rent and Interest,” a paper presented before the American Economic Association, December, 1903. Cf. Clark, Capital and its Earnings, p. 27, and Distribution of Wealth (Macmillan, 1899), Chaps. IX and XIII. Cannan developed the same idea in “What is Capital?” Economic Journal, June, 1897. Cf. the writer’s “ Role of Capital,” Economic Journal, December,1897, pp. 524, 526. 2 Positive Theory of Capital, English translation, London and New York, 1891, p. 38. # Capital, English translation, London, 1887, Vol. II, p. 792. 4 Capital and Interest, Book VI. 8 Wealth of Nations, Book II, Chap. I. ® “Political Economy,” Encyclopedia Metropolitana, Vol. VI, p. 153. " Staatswirtschaftliche Untersuchungen, Munich; 1832, p. 59. Capital and its Earnings, Publications of American Economic Association, 1888, pp. 11-13.