S31
Birth of Commerce, Principle of the valuation[1]of commercial things.
Reciprocal want has led to the exchange of what people have for what they have not. People exchange one kind of produce[2] for another, or produce for labour. In these exchanges it is necessary that the two parties should agree both as to the quality and the quantity of each of the things exchanged. In this agreement it is natural that each should wish to receive as much and give as little as he can; and both being equally masters of what they have to give in the exchange, each has to balance the attachment he has for the commodity he gives against the desire he has for the commodity he wishes to receive, and to fix in accordance therewith the quantity of each of the things exchanged. If the parties are not in accord, it will be necessary that they should approach one another by yielding a little on one side and a little on the other, offering more and contenting themselves with less. I will suppose that one has need of corn, and the other of wine, and that they agree to exchange one bushel of corn for six pints of wine. It is evident that by each of them one bushel of corn and six pints of wine are looked upon as exactly equivalent, and that in this particular exchange the price of a bushel of corn is six pints of wine, and the price of six pints of wine is a bushel of corn. But in another exchange between other men this price will be different, according as one of them happens to have a more or less pressing need of the commodity
