The Wealth of Nations by Part 2 Chapter 3 Page 32

Gold and silver are purchased everywhere in the same manner.

The food, clothing, and lodging, the revenue and maintenance of all those whose labour or stock is employed in bringing them from the mine to the market, is the price paid for them in Peru as well as in England. The country which has this price to pay will never be long without the quantity of those metals which it has occasion for; and no country will ever long retain a quantity which it has no occasion for.

Whatever, therefore, we may imagine the real wealth and revenue of a country to consist in, whether in the value of the annual produce of its land and labour, as plain reason seems to dictate; or in the quantity of the precious metals which circulate within it, as vulgar prejudices suppose; in either view of the matter,