This definition has been indorsed by several other writers; by some, however, the term _money_ is restricted to coin, paper money being called currency. The distinction is perfectly proper, though not generally concurred in. People commonly use the terms _money_ and _currency_ indiscriminately for both coin and paper money, since they perform identically the same work where both are used together, and the paper is convertible into coin at any time. Where the paper is used alone--"inconvertible paper"--coin is really not money; it ceases to circulate as money; it is hoarded as treasure, or bought and sold as a commodity, but fails to have that general use in current transactions in that country which alone entitles any commodity to be called money. The distinction sought to be made between paper money and coin arises largely, it is thought, from the idea that coin has a value in itself which paper money has not. This idea is erroneous. Value, as we have seen, is a ratio or relation, and though the value of anything is based on a desire for it, that desire may arise either from the satisfaction which the use or consumption of it will bring, or from the belief that it can be exchanged for some other thing that will give satisfaction in use or consumption. The value of money is due to the latter of these two causes. No one wants money except for the purpose of exchanging it for other commodities; under modern conditions it is necessary for this purpose,--it is the indispensable requisite to the satisfaction of certain human wants. Money, therefore, possesses an indirect if not a direct subjective value which forms the basis of its exchange value. Paper money possesses the power of satisfying this need for money to the same extent that coin does, under like conditions, and it has, therefore, both subjective value and exchange value, and the latter is governed by the same law of supply and demand that operates in all cases. The fact that the material of which the money is made is, in one instance, of great cost, and, in the other, of little or no cost, is of minor consequence. The minting of gold and silver into coin may, or may not, add to its value; it really transforms it into another commodity--money--and its value is thenceforth determined by the law of supply and demand as applied to money. The same is true of paper money, the low cost in the production of which is not an element in determining its value, for its production is always a monopoly. There is no reason, then, for not considering paper currency as money, and in using the term we will consider its meaning to be that given by Professor Walker,--which is also its popular significance,--and as including both paper money and coin.