9.--The determination of the relation between the living wage for men and women is one of the difficult questions that will have to be met in the course of the enforcement of any living wage policy. The position of women, both in industry and in society is at present undergoing change. The limit and direction of this change cannot be marked out with certainty. Therefore, the presuppositions upon which present policy may be constructed may become invalid in a comparatively short time. The unsatisfactoriness of leaving the question to be settled by the decision of the market has become increasingly plain. That policy produces, on the one hand, a constant effort on the part of the employers to so modify their processes of production as to take advantage of the low range of women's wages, irrespective of the effect on men's wages and of the suitability of the occupation in question for women; and, on the other hand, a constant effort on the part of the men to keep the women out of all new employments. The best advised foundation for present policy, in my opinion, is the two separate bases of assessment, suggested above.[130] In its favor, it may be pointed out that it corresponds to a certain extent to the existing relation between the wages of men and women in industry, and it would not, therefore, produce any violent change. Its unsatisfactoriness lies in the possibility that it may gradually lead to a displacement of men by women in many employments. On the question of whether such displacement is to be desired, there is room for the very deepest differences of opinion. It seems to me, however, that the industrial history of the nineteenth century proves the supreme importance of the wage of the head of the family to the general welfare of the family. For that reason, it is, in my opinion, wise to protect the wage of the male head of the family; and thus to provide that when men and women are employed upon the same work or when women are introduced into employments hitherto filled by men, the wage rates for men should be enforced throughout the employment. This ruling could be interpreted in some cases in terms of the relative efficiency of men and women, if there was a clear difference of efficiency. Of course, if the term "relative efficiency" is construed to include the difference in the indirect or overhead expense involved in the employment of male or female labor in any occupation, such a policy would amount to throwing open every field of employment to women.