Whoever derives his revenue from a fund, which is his own, must draw it either from his labor, from his stock, or from his land. The revenue derived from labor is called wagesThat derived from stock, by the person who manages or employs it, is called profit. That derived from it by the person who does not employ it himself, but lends it to another, is called the interest or the use of money. The revenue which proceeds altogether from land, is called rent, and belongs to the landlord. The revenue of the farmer is derived partly from his labor, and partly from his stock. To him, land is only the instrument which enables him to earn the wages of this labor, and to make the profits of this stock.fg

the source and as a method of exchange.

“Agriculture is the sole source of wealth of a nation” – Adam Smith