In a general and uncertain way this holds true, but the test is not so readily applied nor so conclusive as might be wished. There are several assignable reasons for its partial failure. All classes are in a measure engaged in the pecuniary struggle, and in all classes the possession of the pecuniary traits counts towards the success and survival of the individual. Wherever the pecuniary culture prevails, the selective process by which men's habits of thought are shaped, and by which the survival of rival lines of descent is decided, proceeds proximately on the basis of fitness for acquisition. Consequently, if it were not for the fact that pecuniary efficiency is on the whole incompatible with industrial efficiency, the selective action of all occupations would tend to the unmitigated dominance of the pecuniary temperament. The result would be the installation of what has been known as the "economic man," as the normal and definitive type of human nature. But the "economic man," whose only interest is the self-regarding one and whose only human trait is prudence is useless for the purposes of modern industry. The modern industry requires an impersonal, non-invidious interest in the work in hand. Without this the elaborate processes of industry would be impossible, and would, indeed, never have been conceived. This interest in work differentiates the workman from the criminal on the one hand, and from the captain of industry on the other. Since work must be done in order to the continued life of the community, there results a qualified selection favoring the spiritual aptitude for work, within a certain range of occupations. This much, however, is to be conceded, that even within the industrial occupations the selective elimination of the pecuniary traits is an uncertain process, and that there is consequently an appreciable survival of the barbarian temperament even within these occupations. On this account there is at present no broad distinction in this respect between the leisure-class character and the character of the common run of the population.