So long as man's mastery of the forces of nature is incomplete, said Nietzsche, it will be necessary for the vast majority of human beings to spend their lives in either supplementing those natural forces which are partly under control or in opposing those which are still unleashed. The business of tilling the soil, for example, is still largely a matter of muscular exertion, despite the vast improvement in farm implements, and it will probably remain so for centuries to come. Since such labor is necessarily mere drudgery, and in consequence unpleasant, it is plain that it should be given over to men whose realization of its unpleasantness is least acute. Going further, it is plain that this work will be done with less and less revolt and less and less driving, as we evolve a class whose ambition to engage in more inviting pursuits grows smaller and smaller. In a word, the ideal ploughman is one who has no thought of anything higher and better than ploughing. Therefore, argued Nietzsche, the proper performance of the manual labor of the world makes it necessary that we have a laboring class, which means a class content to obey without fear or question. This doctrine brought down upon Nietzsche's head the pious wrath of all the world's humanitarians, but empiric experiment has more than once proved its truth. The history of the hopelessly futile and fatuous effort to improve the negroes of the Southern United States by education affords one such proof. It is apparent, on brief reflection, that the negro, no matter how much he is educated, must remain, as a race, in a condition of subservience; that he must remain the inferior of the stronger and more intelligent white man so long as he retains racial differentiation. Therefore, the effort to educate him has awakened in his mind ambitions and aspirations which, in the very nature of things, must go unrealized, and so, while gaining nothing whatever materially, he has lost all his old contentment, peace of mind and happiness. Indeed, it is a commonplace of observation in the United States that the educated and refined negro is invariably a hopeless, melancholy, embittered and despairing man.