But if we now see that the three classes of modern society, the feudal aristocracy, the bourgeoisie and the proletarian, have their distinctive ethical systems, we can only conclude therefrom that mankind consciously or unconsciously shapes its moral views in accordance with the material facts upon which in the last instance the class existence is based--upon the economic conditions under which production and exchange are carried on. But in the three above mentioned systems of ethics there is much which is common to all three of them, and might not this at least constitute a portion of an eternally stable system of ethics? These ethical theories pass through three distinct steps in their historical development, they have therefore a common historical basis and hence necessarily much in common. Further, for approximately similar economic stages there must, necessarily be a coincidence of similar stages of economic development, and ethical theories must of necessity coincide with a greater or less degree of closeness. From the very moment when private property in movables developed there had to be ethical sanctions of general effect in all communities in which private property prevailed, thus: Thou shalt not steal. Is this commandment, then, an eternal commandment? By no means. In a society in which the motive for theft did not exist stealing would only be the practice of the weak-minded, and the preacher of morals who proclaimed "Thou shalt not steal" as an eternal commandment would only be laughed at for his pains.