There are certain qualities essential to a good money material which makes certain of the metals, and especially the precious metals, peculiarly suitable. Among these qualities are general desirability, portability, durability, homogeneity, divisibility, stability of value, and cognizability.

In the first place, the material should be generally desired in order that it may itself have value; for unless the money has value it cannot serve to measure value in other commodities, and unless it is generally desired it will not be accepted as a medium of exchange. The money should be portable; that is, its weight and bulk should be small as compared with its value, so that it may be transported for purposes of exchange. Lycurgus, the legend says, gave the Spartans an iron money in order to keep them from becoming a commercial nation; but statesmen to-day desire to advance commerce rather than to retard it. The money material should be durable so that it may be kept over a considerable period of time without deteriorating in quality and consequently losing part of its value. The money material should be homogeneous, that is, of the same quality throughout, so that equal weights will have equal value. Where two or more metals are used for money at the same time, however, as for example gold and silver, it is not important that a given weight of one should equal in value the same weight of the other, provided that they are readily distinguishable from one another and that one will not be taken for the other. Money should be divisible in the sense that it should be possible to cut the material into pieces without a diminution in value. The value of the parts should be equal to the value of the whole out of which the parts are made. The money material should possess stability of value in order that it may serve as a standard of deferred payment. It is important for the debtor to know how much value he is to return at the end of a year or five years, and this is not possible where there is not some standard of value which remains fairly constant. By the cognizability of the material of the money is meant its quality of being easily recognized so that there is no doubt to the persons who receive it as to just what it is. A material that can be made into coins and that will hold the impression that is made upon it possesses cognizability in a high degree. The metals, and especially the precious metals, have been found to possess these qualities so preeminently that they have come to be the basis of the money of the civilized world.