But Exchange has given rise to the separation of occupations, or, in other words, to the establishment of trades and professions. Each service (or each product) has, then, two relations, one with the person who furnishes it, and the other with the person who receives it.

Undoubtedly, at the end of the evolution, man in a social state, like man in a state of isolation, is at once producer and consumer, but we must see clearly the difference. Man in an isolated state is always the producer of the very thing he consumes, which almost never happens with man in the social state. This is an unquestionable fact, which every one can verify for himself. It [p129] follows, moreover, from this that the social state consists in an interchange of services.

We are all producers and consumers, not of the thing, but of the value, that we have produced. In exchanging commodities we remain always possessed of their value.

It is this which gives rise to all economic errors and illusions, and it may not be useless to mark here the progress of the human mind in this respect.

We give the general name of obstacle to everything which, being interposed between our wants and our satisfactions, calls for the intervention of our efforts.

The relations of these four elements—want, obstacle, effort, satisfaction—are quite apparent, and easily understood in isolated man. We should never think of saying—

“It is a pity that Robinson Crusoe did not encounter more obstacles, for in that case he would have had more opportunities of exerting his energies—he would have been richer.”

“It is unfortunate that the sea should have cast upon the shore of the desert island useful articles, such as timber, provisions, arms, books; for this deprived him of the opportunity of exerting himself—it made him less rich.”

“It is to be regretted that Robinson invented nets to take fish and game, for that diminished by so much his efforts in relation to each given result—it made him less rich.”

“It is a pity that Robinson was not more frequently sick, for then he must have set to doctoring himself, which is labour; and as all wealth comes from labour, he would have been more wealthy on that account.”