La′bor is effort made for the satisfying of human needs. It is one of the three leading-factors in production, the others being land and capital. It is of more importance than the other two, for without labor land could not be made productive and capital could not result. Productive labor is that which produces what is necessary for man's use; unproductive labor, like that of the musician, is that which does not add to material wealth. In the early years of the world's history men performed the labor of the chase, fishing and like pursuits, and women and slaves performed the drudgery. Compulsory labor formed the basis of ancient civilization. The pyramids of Egypt and other great works were possible because the authorities could command forced labor. Slavery and serfdom are forms of forced labor. Toward the close of the 18th century labor began to be organized in large factories, with the result that great changes have taken place in the condition of the workmen. Trade-unions and co-operative societies have sprung up, and the workingman's admission to the franchise has made organized labor a powerful factor in the political world. The purely wage-workers of the United States, whose average income does not much exceed $475 annually, number over 15,000,000 or three tenths of the population. The Federation of Labor is an organization of American wage-workers, and its object is to obtain the best results for the laboring people by fair and honorable means.