Front Page Titles (by Subject) Quantity of Work to be done by Money. - Money and the Mechanism of Exchange
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Quantity of Work to be done by Money. - William Stanley Jevons, Money and the Mechanism of Exchange 
Money and the Mechanism of Exchange (New York: D. Appleton and Co. 1876).
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Quantity of Work to be done by Money.
To decide how much money is needed by a nation, we must, firstly, determine the quantity of work which money has to do. This will be proportional, ceteris paribus, to the number of the population; twice the number of people, if equally active in trade and performing it in the same way, will clearly want twice as much money. It will be proportional, again, to the activity of industry, and to the complexity of its organization. The more goods are bought and sold, and the more often they pass from hand to hand, the more currency will be needed to move them. It will be proportional, again, to the prices of goods; and if gold falls in value, and prices are raised, more money will be needed to pay the debts increased in nominal amount.
Few of the quantities concerned in such considerations are known. We know the number of the population approximately, and the amount of foreign trade, but the quantities of goods bought and sold in inland trade are almost entirely unknown. It is needless to dwell on this side of the question, as our knowledge is still more defective in other respects.