With but slight qualification, it will hold that, in the causal sequence which Adam Smith traces out in his economic theories proper (contained in the first three books of the _Wealth of Nations_), the causally efficient factor is conceived to be human nature in these two relations,--of productive efficiency and pecuniary gain through exchange. Pecuniary gain--gain in the material means of life through barter--furnishes the motive force to the economic activity of the individual; although productive efficiency is the legitimate, normal end of the community's economic life. To such an extent does this concept of man's seeking his ends through "truck, barter, and exchange" pervade Adam Smith's treatment of economic processes that he even states production in its terms, and says that "labor was the first price, the original purchase-money, that was paid for all things."[19] The human nature engaged in this pecuniary traffic is conceived in somewhat hedonistic terms, and the motives and movements of men are normalised to fit the requirements of a hedonistically conceived order of nature. Men are very much alike in their native aptitudes and propensities;[20] and, so far as economic theory need take account of these aptitudes and propensities, they are aptitudes for the production of the "necessaries and conveniences of life," and propensities to secure as great a share of these creature comforts as may be. Adam Smith's conception of normal human nature--that is to say, the human factor which enters causally in the process which economic theory discusses--comes, on the whole, to this: Men exert their force and skill in a mechanical process of production, and their pecuniary sagacity in a competitive process of distribution, with a view to individual gain in the material means of life. These material means are sought in order to the satisfaction of men's natural wants through their consumption. It is true, much else enters into men's endeavors in the struggle for wealth, as Adam Smith points out; but this consumption comprises the legitimate range of incentives, and a theory which concerns itself with the natural course of things need take but incidental account of what does not come legitimately in the natural course. In point of fact, there are appreciable "actual," though scarcely "real," departures from this rule. They are spurious and insubstantial departures, and do not properly come within the purview of the stricter theory. And, since human nature is strikingly uniform, in Adam Smith's apprehension, both the efforts put forth and the consumptive effect accomplished may be put in quantitative terms and treated algebraically, with the result that the entire range of phenomena comprised under the head of consumption need be but incidentally considered; and the theory of production and distribution is complete when the goods or the values have been traced to their disappearance in the hands of their ultimate owners. The reflex effect