There is thus labor that is pleasurable in itself and labor that is painful though it leads to a desirable result. The social ideal clearly is that all human labor should be made pleasurable. Social dreamers love to picture a day when all shall find for effort a full reward in the mere doing,--the reward of the artist, of the scholar, of the saint, in addition to the objective result in economic wealth. Probably we are slowly nearing this ideal. Not only in the professions and in the esthetic arts, but in commerce, in mechanics, and in the humblest walks of life are found men free from envy, rejoicing in their daily tasks. Such is the normal feeling of the healthy optimist. And yet in every serious occupation there are numberless moments and occasions when the spirit flags and only hard necessity holds men to their tasks. The dilettante does not go far or long or steadily; the real tasks of the world are done by men that labor, now with joy, now wearily. [Sidenote: The distinction between men and things] 2. _The agents of production compose two great species, material goods and human services._ Our discussion of consumption goods, rent, and interest has been an analysis of the nature and uses of material goods. We now come to the other great species, human services, which comprise those acts of men (one's own or other's) that minister to the gratification of wants. There are also misdirected efforts, and evil deeds which are "disutilities" to all but the doer. The distinction between men and things is fundamental in modern economic discussion where each man is looked upon as free. It is not so clear where slavery exists and the master looks in the same way upon the services of his cattle, of his chattel slaves, and of his land. Even in the freest society, man's services are compared purely as to their utility, with the uses of other parts of the material world. It is said that the price of mules at the Pennsylvania mines has been affected by immigration, because a man and a mule sometimes represent interchangeable services. But in the study of political economy the distinction between men and other material things must never be lost sight of; they are the two fundamental classes of economic agents, the one being solely a means to an end, the other being an end in itself. [Sidenote: Rent and wages mutually affect each other]