The only motive to a mutual exchange of services, whether in one or in all of their three kinds, that is to say, to a free production of commodities and services and credits, is always and everywhere the mutual benefit of the two parties exchanging. After all the processes have been gone through with and the exchanges are consummated, all the parties are richer than before, that is, they have more _satisfactions_, otherwise the processes and exchanges would instantly cease. Therefore, a universally free production benefits everybody, and harms nobody. Moreover, under a system of free production, every man is allowed under the stimulus of self-interest to work away at those obstacles to the gratification of human desires which he feels himself best able to overcome, to follow the bent of his own mind, and to avail himself of all those free helps in his peculiar work which Nature offers to him. Under these circumstances, obstacles give way in all directions; the amount of material products produced is vastly augmented, the number and variety and excellence of personal services proffered are indefinitely increased, and credits compelling the Future to pay tribute to production are multiplied; the diversified and rapidly increasing desires of all persons in such a community are readily met through profitable exchanges; while all peculiar facilities natural and acquired are taken immediate advantage of, the diversities of relative advantage in production become marked in all directions, and a new day of industrial and commercial prosperity is ushered in. Because under freedom all men are sure to dispose of their industrial efforts to the best advantage, they have the strongest possible motives to put them forth; since they can purchase with them what they will and when they will, and where they will. Thus freedom leads to extended association, and also to the invention of machinery and all labor-saving appliances. 3. We are now in position to understand thoroughly the ultimate GROUNDS of the production of material commodities. We have seen, that these commodities have been multiplying in number and variety and excellence ever since the beginnings of history, that they are everywhere multiplying now at a rate hitherto unprecedented and undreamed of, and that improved and improving methods of transportation by land and sea are now carrying these back and forth to the ends of the earth. What is the _principle_, under which these things have been done, are now being done, and are certain to be done in the time to come?