John Stuart Mill,
Principles of Political Economy
(1871)
“ It thus appears, that a depreciation of the currency does not affect the foreign trade of the country: this is carried on precisely as if the currency maintained its value. But though the trade is not affected, the exchanges are. When the imports and exports are in equilibrium, the exchange, in a metallic currency, would be at par; a bill on France for the equivalent of five sovereigns, would be worth five sovereigns. But five sovereigns, or the quantity of gold contained in them, having come to be worth in England 6l., it follows that a bill on France for 5l. ”
