The Wealth of Nations by Part 4 Chapter 3 Page 7

France and England, or if French goods could be imported upon paying only the same duties as those of other European nations, to be drawn back upon exportation, England might have some share of a trade which is found so advantageous to Holland.

Thirdly, and lastly, there is no certain criterion by which we can determine on which side what is called the balance between any two countries lies, or which of them exports to the greatest value. National prejudice and animosity, prompted always by the private interest of particular traders, are the principles which generally direct our judgment upon all questions concerning it. There are two criterions, however, which have frequently been appealed to upon such occasions, the customhouse books and the course of exchange.

The custom-house books,