Political economy (the economy of a State, or of citizens) consists simply in the production, preservation, and distribution, at fittest time and place, of useful or pleasurable things. The farmer who cuts his hay at the right time; the shipwright who drives his bolts well home in sound wood; the builder who lays good bricks in well-tempered mortar; the housewife who takes care of her furniture in the parlour, and guards against all waste in her kitchen; and the singer who rightly disciplines, and never overstrains her voice: are all political economists in the true and final sense; adding continually to the riches and well-being of the nation to which they belong. But mercantile economy, the economy of "merces" or of "pay," signifies the accumulation, in the hands of individuals, of legal, or moral claim upon, or power over, the labour of others; every such claim implying precisely as much poverty or debt on one side, as it implies riches or right on the other. It does not, therefore, necessarily involve an addition to the actual property, or well-being, of the State in which it exists. But since this commercial wealth, or power over labour, is nearly always convertible at once into real property, while real property is not always convertible at once into power over labour, the idea of riches among active men in civilized nations, generally refers to commercial wealth; and in estimating their possessions, they rather calculate the value of their horses and fields by the number of guineas they could get for them, than the value of their guineas by the number of horses and fields they could buy with them.