The Wealth of Nations by Part 1 Chapter 5 Page 19

is regulated, as I shall likewise endeavour to show hereafter, by the value of silver, by the richness or barrenness of the mines which supply the market with that metal, or by the quantity of labour which must be employed, and consequently of corn which must be consumed, in order to bring any particular quantity of silver from the mine to the market. But the value of silver, though it sometimes varies greatly from century to century, seldom varies much from year to year, but frequently continues the same, or very nearly the same, for half a century or a century together.

The ordinary or average money price of corn, therefore, may, during so long a period, continue the same or very nearly the same too, and along with it the money price of labour, provided, at least, the society continues, in other respects, in the same or