The New Contractarians

This division of labor, from which so many advantages are derived, is not originally the effect of any human wisdom, which forsees and intends that general opulence to which it gives occasion. It is the necessary, though very slow and gradual, consequence of a certain propensity in human nature which has in view no such utility; the propensity to trade, barter, and exchange one thing for another. [This propensity] ... is common to all men, and to be found in no other race of animals, which seem to know neither this nor any other species of contracts.