THERE exists in society a widely-spread error relating to the very principle of that interchange of property between individuals which is usually called a bargain. It is almost always supposed that one party is a gainer whilst the other is a loser. Indeed, by those whose reasoning on the subject has been limited to this single view of the question, it is with some plausibility maintained, that since the quantity of the commodities interchanged is in no case augmented by the bargain, the gain of one party can be accomplished only by an equal loss on the part of the other.