[24] Fisher, Irving, _The Nature of Capital and Income_, New York, 1906, pp. 13 _et seq._ Ely, R. T. (and others). _Outlines of Economics_, New York, 1908, pp. 156-57. Professor Ely uses the term in a different sense on pp. 99-100; and on the pages first cited indicates that value, defined as a quantity of other goods, is to be distinguished from subjective value. But "subjective" (individual) value would hardly serve as an equivalent for the value described on pp. 99-100. There are, in fact, four pretty distinct uses of the term value to be found in Professor Ely's discussion, inadequately distinguished, and often confused in the treatment: (1) homogeneous quality among the diversities of the physical forms of wealth, by virtue of which a sum of wealth may be obtained (99-100); (2) ratio of exchange (156); (3) quantity of goods obtained in exchange (157); (4) subjective utility (157 and _ante_); and a fifth meaning is indicated for market value on pp. 358-59, where, in explaining the law of rent for pleasure grounds and residence sites, the "general law of value" is declared to be that value measures _marginal utility_. _Cf._ the confusions of utility and demand pointed out _infra_, chapter v. This loose treatment of the value concept, while doubtless accentuated by the fact that four men have cooperated in the production of the book, is too much characteristic of most of the text-books. There is even to-day little uniformity or agreement as to what value means. [25] _Natural Value_, p. 53, n.