"This currency is nothing more than the evidence of service having been rendered for which an equivalent has not been received, but which may at any time be demanded. It is obvious that as soon as it has been rendered, the evidence of its being due must be given up to the debtor to be destroyed, and it will be no longer current. And if any man can render services to his neighbours, he must in return receive either other services, or the evidence of their being due; and if he renders more services than he immediately requires in return, he will accumulate a store of this evidence for his future wants. ...It is quite clear that its use is to measure and record debts, and to facilitate their transfer from one person to another; and whatever means be adopted for this purpose, whether it be gold, silver, paper, or anything else, is a currency. We may therefore lay down as our fundamental conception that Currency and Transferable Debt are convertible terms; whatever represents transferable debt of any sort is Currency, and whatever material the currency may consist of, it represents transferable debt and nothing else."