5. _Skill and capacity in industrial tasks is a resultant of many qualities._ The simplest task calls for a combination of force and judgment,--even the digging of a ditch, the raising of a window, or the fitting of a stovepipe. For most industrial tasks rarer combinations of qualities are required. The retail clerk must be neat, punctual, polite, and long suffering. A confidential clerk must have discretion, judgment, and other moral qualities in an unusual combination. The substitution of qualities is possible within limits; a rare quality may make amends for the lack of a commoner one, and a man may, because of peculiar fitness in some regards, continue to hold a position for which in other ways he is little fitted. The rarest and most valued worker is one uniting many good qualities and fitted to deal with emergencies. The economic efficiency of the worker often is no stronger than its weakest link. A strong motive for training is offered by the fact that supplying some one lacking quality may raise the total efficiency in a remarkable degree. [Sidenote: Inequality of talents shown by biologic studies] 6. _Biologic studies have of late made clearer the existence and continuation of the inequality of talents._ The political philosophy of the eighteenth century was based on the idea of natural rights and natural equality. Adam Smith, accepting the prevailing view, discussed wages on the assumption that all men had equal natural ability. It is still a favorite assumption of radical social reformers that the natural ability of all men is equal, and that all the differences in success result from political injustice. The study of biology of late has made patent the unending differences that prevail throughout the animate world. No two members of the same family or species are just alike; no two pigeons have wings of just the same length. Nature by numberless devices is experimenting constantly with variations on either side of the established mean. The accepted fact of biologic evolution rests on the foundation of inequality in structure and powers, making possible selection and adaptation. Men in all their qualities of mind and body display this kaleidescopic variety. In all life there is inequality, and the whole drama of human history as well as that of biologic evolution must be meaningless or illusory to the man who does not see this truth. Accustomed now to this point of view, we as inevitably think of the natural inequalities in men as did Adam Smith of their equality.