The Wealth of Nations by Part 1 Chapter 4 Page 18

First, what is the real measure of this exchangeable value; or, wherein consists the real price of all commodities.

Secondly, what are the different parts of which this real price is composed or made up.

And, lastly, what are the different circumstances which sometimes raise some or all of these different parts of price above, and sometimes sink them below their natural or ordinary rate; or, what are the causes which sometimes hinder the market price, that is, the actual price of commodities, from coinciding exactly with what may be called their natural price.

I shall endeavour to explain, as fully and distinctly as I can, those three subjects in the three following chapters, for which I must very earnestly entreat both the patience and attention of the