It frequently happens that men attribute their larger rewards to larger productivity, when the true determining element is scarcity. The immediate reason why the engine driver receives more than the track repairer, the general manager more than the section foreman, the floorwalker more than the salesgirl, lies in the fact that the former kinds of labour are not so plentiful as the latter. Were general managers relatively as abundant as section foremen their remuneration would be quite as low; and the same principle holds good of every pair of men whose occupations and products are different in kind. Yet the productivity of the general managers would remain as great as before. On the other hand, no matter how plentiful the more productive men may become, they can always command higher rewards than the less productive men in the same occupation, for the simple reason that their products are superior either in quantity or in quality. Men engaged upon the more skilled tasks are likewise mistaken when they attribute their greater compensation to the intrinsic excellence of their occupation. The fact is that the community cares nothing about the relative nobility, or ingenuity, or other inherent quality of industrial tasks or functions. It is concerned solely with products and results. As between two men performing the same task, superior efficiency receives a superior reward because it issues in a larger or better product. As between two men performing different tasks, superior skill receives superior compensation simply because it can command the greater compensation; and it is able to do this because it is scarce. In most cases where scarcity is the immediate determinant of rewards, the ultimate determinant is, partly at least, some kind of sacrifice. One reason why chemists and civil engineers are rarer than common labourers is to be found in the greater cost of preparation. The scarcity of workers in occupations that require no special degree of skill is due to unusual hazards and unpleasantness. In so far as scarcity is caused by the uncommon sacrifices preceding or involved in an occupation, the resulting higher rewards obviously rest upon most solid ethical grounds. However, some part of the differences in scarcity is the result of unequal opportunities. If all young persons had equal facilities of obtaining college and technical training, the supply of the higher kinds of labour would be considerably larger than it now is, and the compensation would be considerably smaller. Scarcity would then be determined by only three factors; namely, varying costs of training, varying degrees of danger and unattractiveness among occupations, and inequalities in the distribution of native ability. As a consequence, competition would tend to apportion rewards according to efforts, sacrifices, and efficiency.