_Fidelity as affecting the Productivity of Labor._--The fact that all workmen are largely their own directors brings fidelity into the foreground as an element in determining men's earning power; but this element counts for much more in the civilized state than it does in the primitive one, for here fidelity in directive laborers of the highest type is most important and difficult to secure. One of the greatest problems of modern business is how to make directors and executive officers of corporations faithful to the stockholders who employ them. In the primitive state these problems do not arise. When a man is working for himself, mere interest largely takes the place of fidelity. If to-day any one secures a good house of his own to live in, it is because he employs contractors, overseers, and artisans all of whom are, in the main, faithful to his interests and see that the work of building is properly done. A savage looks after his own interests as his personal work proceeds; and yet even in his case there is the germ of that enthronement of character in the supreme place which is the prominent feature of highly organized industry. In building a hut to shelter his family, a savage puts into his work conscience and affection as well as muscular effort; and when the mother of the family does this work, the altruistic element in it is still more conspicuous. As society becomes highly organized the importance of the moral element in all labor increases till the further progress, or even the existence, of the social order may be said to depend on it. In the world of business there is now distrust and turmoil, and revolutions are feared, because of the unfaithfulness of a class of men to trusts committed to them.[6] [6] On the ground of convenience, we may classify labor as physical or mental, according as the work of muscle or of brain is especially prominent. Digging a ditch requires more than an average amount of strength and not even an average amount of intelligence, and it is, therefore, physical labor rather than mental; while writing a brief or arguing a case in court requires much power of thought and only a small amount of muscular strength, and is typically mental labor. Managing an estate for an absent owner is more largely a moral function, since the value of the service depends chiefly on the fidelity of the man who renders it; but physical and intellectual labor are also involved. These three types of personal effort are exerted wherever wealth is created.