[189] The reader will understand that I am using accustomed phraseology and making customary assumptions, not because I approve of them, but because the point at issue here is not affected by the question as to the relations between value and utility, etc. The distinction between a utility curve and a price curve does not affect the argument here. [190] Analytically expressed _xy_ = _c_. This curve, by definition, leaves the "value area" (_xy_) constant. [191] A complication must be noticed here, due to my use of the term, "demand curve." I am tacitly assuming that the absolute value of the money unit remains the same in this process, and so must say that the English School would concede that the value of the money unit has doubled even though holding that all the other values remain unchanged, except with reference to the money unit. For Professor Seligman, the value of money (_i.e._, the total stock) has not changed. [192] But the limitation is not absolute. New incentives may call out substantial increases in productive activity. [193] Written by Professor W. M. Urban, author of _Valuation_, to which frequent reference has been made. _Vide Valuation_, p. 4, n. The article was, of course, written several years before the book. [194] In this view I am sustained by Professor John Dewey. [195] _Cf._ Stuart, "Valuation as a Logical Process," in Dewey's _Studies in Logical Theory_, pp. 328, n., and 330. [196] See _supra_, p. 165, n. [197] "La psychologie en economie politique," _Rev. Philosophique_, vol. XII, p. 238. CHAPTER XVII THE THEORY OF VALUE AND THE THEORY OF PRICES