The Wealth of Nations by Part 4 Chapter 3 Page 10

But though the ordinary course of exchange should be allowed to be a sufficient indication of the ordinary state of debt and credit between any two places, it would not from thence follow that the balance of trade was in favour of that place which had the ordinary state of debt and credit in its favour. The ordinary state of debt and credit between any two places is not always entirely regulated by the ordinary course of their dealings with one another; but is often influenced by that of the dealings of either with many other places. If it is usual, for example, for the merchants of England to pay for the goods which they buy of Hamburg, Danzig, Riga, etc., by bills upon Holland, the ordinary state of debt and credit between England and Holland will not be regulated entirely by the ordinary course of the dealings of those two countries with one another, but