In short, under any scheme of wage relationship based on the preservation of existing differentials, it could not be established in the face of any claim that the relative position of a group was determined either by consideration of justice, or by implacable necessity. Therefore, that scheme would not receive the constant and widespread support requisite to its successful operation.[139] So far then, in this chapter, two conclusions have been reached. Firstly, that the course of wage settlement in each industry or occupation cannot be a process entirely independent from the course of wage settlement in every other industry and occupation. Secondly, that although the first step in the establishment of any scheme of wage relationship is the acceptance of existing wage levels and differentials, the policy must provide for the reconsideration of these differentials in the light of affirmed principles; with the aim of gradually evolving in industry an ordered scheme of wage relationship, upheld by common consent to the principles on which it rests. 4.--Thus we are put under the necessity of attempting to formulate principles or standards by which all claims made by groups of wage earners for reconsideration of existing wage differentials could be judged. This is not a task to be lightly undertaken. Nor is it to be expected that such clear principles of wage relationship can be elaborated as to escape the necessity of deciding many claims by an appeal to compromise and by taking refuge in a general sense of equity. All that it is hoped to do is to suggest certain lines along which a satisfactory formulation of the required principles of wage relationship may be sought. It might be possible gradually to construct such an ordered scheme of wage relationship as has been declared essential to industrial peace by applying to successive wage controversies, as they arose, two central doctrines. These doctrines are: Firstly, the doctrine of the unity of the wage income and of the wage earners--by which is meant that the wages of all groups should be regarded as part of one general wage income, to be shared out among all wage earners in as nearly equal proportions, as is practicable, without special favor to any one. And, secondly, what may be called for a lack of a better name, the doctrine of special reward--by which is meant, that the wage differentials between the standard wage levels of different types of labor should be regarded as special rewards, given in order to make it reasonably certain that industry will be provided with at least the existing proportion of the more skilled grades of labor, and to make it reasonably certain also that the more arduous, irregular, dangerous and disagreeable work will command the service of as much labor as at present.