The Wealth of Nations by Part 1 Chapter 11 Page 128

counterbalanced by the continually increasing price of cattle, the principal instruments of agriculture. Upon all these accounts, therefore, we may rest assured that equal quantities of corn will, in every state of society, in every stage of improvement, more nearly represent, or be equivalent to, equal quantities of labour than equal quantities of any other part of the rude produce of land.

Corn, accordingly, it has already been observed, is, in all the different stages of wealth and improvement, a more accurate measure of value than any other commodity or set of commodities. In all those different stages, therefore, we can judge better of the real value of silver by comparing it with corn than by comparing it with any other commodity or set of commodities.

Corn, besides, or whatever