Since gold itself may become, both as coin and bullion, a token of value of greater or smaller magnitude than its bullion value, it is self understood that convertible bank-notes in circulation have to share the same fate. Although bank-notes are convertible, i. e. their real value and nominal value agree, “the aggregate currency consisting of metal and of convertible notes” may appreciate or depreciate according as to whether it rises or falls, for reasons already stated, above or below the level determined by the exchange value of the commodities in circulation and the bullion value of gold. Inconvertible paper money, has, from this point of view, only that advantage as against convertible paper money, that it may depreciate in a two-fold manner. It may fall below the value of the metal which it is supposed to represent, because it has been issued in too great quantity, or it may depreciate because the metal it represents has itself fallen in value. This depreciation, not of paper as compared with gold, but of gold and paper together, or of the aggregate currency of a country, is one of the principal discoveries of Ricardo, which Lord Overstone and Co. pressed into their service and made a fundamental principle of Sir Robert Peele’s Bank legislation of 1844
What should have been proven was that the price of commodities or the value of gold depends on the quantity of gold in circulation. The proof consists in the assumption of what is to be proven, viz. that any quantity of the precious metal employed as money must become a medium of circulation or coin, and thereby a token of value for the commodities in circulation, no matter in what proportion to its own intrinsic value and no matter what the total value of those commodities may be. To put it differently, the proof consists in overlooking all the other functions which money performs besides its function of a medium of circulation. When hard pressed, as in his controversy with Bosanquet, Ricardo, completely under the influence of the phenomenon of depreciated tokens of value caused by their quality, takes recourse to dogmatic assurances.138