The Wealth of Nations by Part 1 Chapter 11 Page 202

will be, much cheaper than gold; yet in another sense gold may, perhaps, in the present state of the Spanish market, be said to be somewhat cheaper than silver.

A commodity may be said to be dear or cheap, not only according to the absolute greatness or smallness of its usual price, but according as that price is more or less above the lowest for which it is possible to bring it to market for any considerable time together. This lowest price is that which barely replaces, with a moderate profit, the stock which must be employed in bringing the commodity thither. It is the price which affords nothing to the landlord, of which rent makes not any component part, but which resolves itself altogether into wages and profit. But, in the present state of the Spanish market, gold is certainly somewhat nearer to this lowest price