The Wealth of Nations by Part 4 Chapter 1 Page 55

is generally more employed in supplying the wants, and carrying out the superfluities of his own, than of any other particular country. To import the gold and silver which may be wanted into the countries which have no mines is, no doubt, a part of the business of foreign commerce. It is, however, a most insignificant part of it. A country which carried on foreign trade merely upon this account could scarce have occasion to freight a ship in a century.

It is not by the importation of gold and silver that the discovery of America has enriched Europe.

By the abundance of the American mines, those metals have become cheaper. A service of plate can now be purchased for about a third part of the corn, or a third part of the labour, which it would have cost in the fifteenth century.