Plausible as this rule may appear, it is impracticable, inequitable, and unjust. In the vast majority of labour contracts it is impossible to know whether both parties obtain the same quantity of net advantage. The gains of the employer can, indeed, be frequently measured in terms of money, being the difference between the wages paid to and the specific product turned out by the labourer. In the case of the labourer no such process of deduction is possible; for advantage and expenditure are incommensurable. We cannot subtract the labourer's privation, that is, his expenditure of time and energy, from his gross advantage, that is, his wages. How can we know or measure the net benefit obtained by a man who shovels sand ten hours for a wage of two dollars? How can we deduct his pain-cost from or weigh it against his compensation? So far as the two sets of advantages are comparable at all, those of the employé would seem to be always greater than those of the employer. A wage of seventy-five cents a day enables the labourer to satisfy the most important wants of life. Weighed against this gross advantage, his pain-cost of toil is relatively insignificant. His net advantage is the greatest that a man can enjoy, the continuation of his existence. The net advantage received by the employer from such a wage contract is but a few cents, the equivalent of a cigar or two. Even if the wage be raised to the highest level yet reached by any wage earner, the net advantage to the labourer, namely, his livelihood, will be greater than the net advantage to the employer from that single contract. Moreover, the sum total of an employer's gains from all his labour contracts is less quantitatively than the sum total of the gains obtained by all his employés. The latter gains provide for many livelihoods, the former for only one. Again, no general rate of wages could be devised which would enable all the members of a labour group to gain equally. Differences in health, strength, and intelligence would cause differences in the pain-cost involved in a given amount of labour; while differences in desires, standards of living, and skill in spending would bring about differences in the satisfactions derived from the same compensation. Finally, various employers would obtain various money gains from the same wage outlay, and various advantages from the same money gains. Hence if the rule of equality of net advantages were practicable it would be inequitable. It is also fundamentally unjust because it ignores the moral claims of needs, efforts, and sacrifices as regards the labourer. As we have seen in the chapter on profits in competitive conditions, and as we shall have occasion to recognise again in a later chapter, no canon or scheme of distributive justice is acceptable that does not give adequate consideration to these fundamental attributes of human personality. _The Rule of Free Contract_