The Wealth of Nations by Part 1 Chapter 11 Page 140

great abundance; for they could not otherwise be times of opulence and prosperity. Corn is a necessary, silver is only a superfluity.

Whatever, therefore, may have been the increase in the quantity of the precious metals, which, during the period between the middle of the fourteenth and that of the sixteenth century, arose from the increase of wealth and improvement, it could have no tendency to diminish their value either in Great Britain or in any other part of Europe.

If those who have collected the prices of things in ancient times, therefore, had, during this period, no reason to infer the diminution of the value of silver, from any observations which they had made upon the prices either of corn or of other commodities, they had still less reason to infer it from any supposed increase of wealth and improvement.