1. As material things differ in their fitness to gratify wants, so do men differ in their powers of labor. The fields, hammers, plows, tools, and machinery of different kinds and qualities have been seen to grade off from the best to the poorest. The poorest, discarded or just about to be discarded, are no-rent agents. The utility felt and recognized in the better qualities is expressed in the rents they yield. Recognizing the variety and inequality of human talent, some economists of late speak of the "rent" of ability, meaning that, like land rent, the greater utility (and corresponding reward) of some labor as compared with others, reflects the difference in the quality of agents. But this expression, though often met in contemporary economic writings, is one to be avoided because it tends to blur the essential distinction between human and other agents. Pursuing the same analogy some economists have talked of capitalizing the worker, - expressing in a lump sum the value of the man as the present worth of the series of incomes which he may be expected to earn in his working life. This, also, is to be avoided, for while possibly it is suggestive in studying some problems, it is on the whole a misleading analogy, dimming the distinction between free-workers and owned and exchangeable wealth.

Grades of labor are analagous to grades of wealth.

Physical differences among men.

2. The physical strength of workers differs according to age, individual, race, and sex. Differences due to age are the most obvious. The child, at first weak, grows toward his maximum of physical strength, which he attains before his fullest intellectual capacity. The period of maximum physical working power lasts fifteen to twenty-five years according to the individual, and then gradually declines as the old worker approaches again the inefficiency of the child. Mental efficiency develops more slowly and longer, the highest qualities of judgment and wisdom being the fruits only of a life rich in experiences. Families and strains of stock differ notably in physical and mental powers; one excels in stature, another in development of muscle. The differences within families are inexplicable, sometimes one brother excelling in one thing, the other in another. The physically perfect man is a rare product. Among three thousand students are but two score endowed with the remarkable combination of lungs, heart, muscle, nerve, and character, that makes possible the finest athletes. The national and racial differences in working power, even in the simplest tasks, are marked but difficult to explain, as so many influences of customs, habits of life, and varieties of diet modify the result. We cannot tell how much of the Englishman's great superiority over the East Indiaman is due to individual, native differences of mind and body, how much to the social environment in which they have lived. Certainly, though, the difference is not mainly one in size; in the Chinese War the little brown men of Japan outmarched all the others. Certainly fiber counts for more than bulk, and character for more than muscle.

A difference in the physical strength of the sexes is found in some degree throughout the world, but it would appear to be far more marked in civilized than in savage communities. Compare the records at the Vassar field-games with that of the men in any leading college: in the hundred-yard dash, fifteen seconds as against ten and a fraction; in the high jump, forty-eight inches as against six feet and over. The muscular force of American college women as tested in the Yale and the Oberlin gymnasiums is but one third that of men, that is, taking all the students, the weaklings and the little men along with the athletes, and the women large and small. As to strength of back the average for men is 154 kilograms, for women 54 kilograms; legs, average for men 186, average for women 76.5; right forearm, average for men 56, average for women 21.4. This is an abnormal difference. The natural and possible strength is more nearly attained by men than by women under our social conditions. Women escape the physical toil which strengthens, but not the mental strain which kills) Men carry more of the wood,) but the women not less of the worries. A fairer test is applied among peasants in field-work in France and Germany, where the strength of women is found to be about two thirds that of men. American women should do and will do more to attain their natural strength when we attain sounder ideas of education and saner modes of living. 3. Differences in intelligence are a resultant of native talent and acquired ability. It is difficult to distinguish these two factors sharply. Two men sitting side by side in an examination, get the same grade; one of them has had excellent preparation from childhood, and all the opportunities that money, travel, and cultured associates can give; the other, under great difficulties, has prepared in a country district school with a little coaching now and then, and struggling against great odds, has at last entered college. The same grade does not mean that their natural ability or even their efficiency in this particular class, is equal. Yet the grade is the best expression to be had of their efficiency in the particular work. Native intelligence shortens the time needed for preparation in any calling; hastens new methods; decreases the cost of supervision; saves materials, tools, and time; diminishes loss from breakage; makes possible the use of finer machinery and better appliances, and imparts those subtler qualities that distinguish the best from the mediocre products. Education and native talent are in a degree interchangeable; one supplements the other. Education increases adaptability; the trained mind will outstrip the untrained mind of greater power. It makes direction easier, fits for higher tasks, and decreases the difficulty of cooperation. Any ability may be helped by education in the broad and true sense, though a fool cannot be made wise by training, and though many a potential genius doubtless has been dwarfed in dusty school-rooms by stupid teachers.

Comparative strength of men and women.

Talent and training as factors of efficiency.

The moral qualities required in industry.