“With regard to men, he must know how to stimulate ambition, how to exercise discipline with firmness, and at the same time with sufficient kindness to insure the good-will and cooperation of all. The more thoroughly he is versed in questions of economics and sociology, the better prepared will he be to meet the problems that will daily confront him. As economic production depends not only on equipment and plant, but on the psychological effect of wage systems, he must be able to discriminate in regard to which wage system is best applicable to certain classes of product.”