of labour is so poorly paid now is the fact that it is very plentiful, a condition which is in turn due to the unequal division of industrial opportunity. Were the opportunities of technical education and of entrance to the higher crafts and professions more widely diffused, the labourers offering themselves for the disagreeable tasks would be scarcer and their remuneration correspondingly larger. This would be not only more comfortable to the abstract principles of justice, but more conducive to social efficiency. To sum up the discussion concerning the canon of efforts and sacrifices: Labourers have a just claim to more than living wages whenever they put forth unusual efforts, and whenever their occupations involve unusual sacrifices, either through costs of preparation, exceptional hazards, or inherent disagreeableness. The precise amount of extra compensation due under any of these heads can be determined, as a rule, only approximately. The next canon to be considered as a reason for more than living wages is that of productivity. This offers little difficulty; for the unusual product is always visible among men who are performing the same kind of work, and the employer is always willing to give the producer of it extra compensation. While superior productive power which is based solely upon superior native ability has only presumptive validity as a canon of justice, that is ethically sufficient in our workaday world. Moreover, the canon of human welfare demands that superior productivity receive superior rewards, so long as these are necessary to evoke the maximum net product. The canon of scarcity has exactly the same value as that of productivity. Society and the employer are well advised and are justified in giving extra compensation to scarce forms of labour when the product is regarded as worth the corresponding price. This remains true even when the scarcity is due to restricted opportunity of preparation, rather than to sacrifices of any sort. In that case the higher rewards are as fully justified as the superior remuneration of that superior productivity which is based upon exceptional native endowments. The amount of extra compensation which may properly be given on account of scarcity is determined either by the degree of sacrifice involved or by the ordinary operation of competition. When men are scarce because they have made exceptional sacrifices of preparation, they ought to be rewarded in full proportion to these sacrifices. When they are scarce merely because of exceptional opportunities, their extra compensation should not exceed the amount that automatically comes to them through the interplay of supply and demand. The canon of human welfare has already received implicit application. When due regard is given to efforts, sacrifices, productivity, and scarcity, the demands of human welfare, both in its individual and its social aspects, are sufficiently safeguarded.