In this sense we may say that labor is a commodity. The emotional associations which people, under the influence of Marxism, attach to this term do not matter. It suffices to observe incidentally that the employers deal with labor as they do with commodities because the conduct of the consumers forces them to proceed in this way. It is not permissible to speak of labor and wages in general without resorting to certain restrictions. A uniform type of labor or a general rate of wages do not exist.
Labor is very different in quality, and each kind of labor renders specific services.
Between the appraisal of the performance of a surgeon and that of a stevedore there is no direct connection. But indirectly each sector of the labor market is connected with all other sectors. An increase in the demand for surgical services, however great, will not make stevedores flock into the practice of surgery. Yet the lines between the various sectors of the labor market are not sharply drawn. There prevails a continuous tendency for workers to shift from their branch to other similar occupations in which conditions seem to offer better opportunities.