17 There is another cause, though more limited in its operation, which checks the wrong balance of trade, to every particular nation to which the kingdom trades. When we import more goods than we export, the exchange turns against us, and this becomes a new encouragement to export, as much as the charge of carriage and insurance of the money which becomes due would amount to. For the exchange can never rise higher than that sum.

18 It must carefully be remarked that throughout this discourse, wherever I speak of the level of money I mean always its proportional level to the commodities, labour, industry, and skill which is in the several states; and I assert that where these advantages are double, treble, quadruple to what they are in the neighbouring states, the money infallibly will also be double, treble, quadruple. The only circumstance that can obstruct the exactness of these proportions is the expense of transporting the commodities from one place to another, and this expense is sometimes unequal. Thus the corn, cattle, cheese, butter of Derbyshire cannot draw the money of London so much as the manufactures of London draw the money of Derbyshire. But this objection is only a seeming one, for so far as the transport of commodities is expensive, so far is the communication between the places obstructed and imperfect.