... individuals can 1 See Knight, Bisk, uncertainty, and Profit; Hicks, The Theory of Profit(Economica, No. 31, pp. 17 0 -19 0).' See Mises, The Theory of Money, pp. 14 7 and 200; Lavington, The English ... xxiï., 19 09).80 SIGNIFICANCE OF ECONOMIC SCIENCE OH.tions of the broad principles of the natural sciences, soin the application of economic principles we must becareful to enquire concerning the ... substitutability of different goods, of the demandfor one good in terms of another, of an equilibriumdistribution of goods between different uses, of equi-librium of exchange and of the formation of prices....