Take now, in connection with the six heads mentioned as governing the present efficiency of labor, the five enumerated by Adam Smith in his summary of causes for differences in wages: 1. "The agreeableness or disagreeableness of the employments themselves. 2. The easiness and cheapness, or the difficulty and expense of learning them. 3. The constancy or inconstancy of employment in them. 4. The small or great trust which must be reposed in those who exercise them. 5. The probability or improbability of success in them." These are conditions which affect the man's right to large or small wage; but all of them presuppose that men are perfectly free to look over the whole industrial field and choose their own employment,--they presuppose the perfect mobility of labor. Let us see what this means. The theoretical mobility of labor rests upon the assumption that laborers of every order will in all ways and at all times pursue their economic interests; but the actual fact is that so far from seeking labor under the most perfect conditions for obtaining it, nearly half of all humankind are "bound in fetters of race and speech and religion and caste, of tradition and habit and ignorance of the world, of poverty and ineptitude and inertia, which practically exclude them from the competitions of the world's industry." "Man is, of all sorts of luggage, the most difficult to be transported," was written by Adam Smith long ago; and this stands in the way of really free and unhampered competition. Mr. Frederick Harrison, one of the clearest thinkers of the day, has well defined the difference between the seller and the producer of a commodity. He says:-- "In most cases the seller of a commodity can send it or carry it from place to place, and market to market, with perfect ease. He need not be on the spot; he generally can send a sample; he usually treats by correspondence. A merchant sits in his counting-room, and by a few letters and forms transports and distributes the subsistence of a whole city from continent to continent. In other cases, as the shopkeeper, the ebb and flow of passing multitudes supplies the want of locomotion for him. This is a true market. Here competition acts rapidly, fully, simply, fairly. It is totally otherwise with a day laborer who has no commodity to sell. He must himself be present at every market, which means costly, personal locomotion. He cannot correspond with his employer; he cannot send a sample of his strength, nor do employers knock at his cottage door."