It should be considered, whether of one material or of several circulating concurrently, as a single commodity created for the purpose it fulfils, and as separate and distinct from the material of which it is made. In short, as that commodity to which, by common consent and usage, generally sanctioned by law, all other commodities are referred as a measure of value, and by means of which exchanges are effected. _The Functions and Requirements of Money._ Professor Jevons, in his valuable work, "Money and the Mechanism of Exchange," gives to money the following threefold functions, viz. as:-- A medium of exchange. A measure of value. A standard of deferred payments. He also inquires if it does not perform a fourth function as a 'store of value.' All authorities give the first two of the above as the principal money functions. Some include one or both of the others, and some omit both. Prof. F. A. Walker objects to the use of the term "measure of value," on the ground that value, being a relation, cannot be measured but can only be expressed. He proposes, instead, the term, "common denominator of value." It is not quite clear why a relation _or_ ratio cannot be measured,--the measure, of course, being a similar ratio,--nor does there seem to be anything gained by the change, while the term proposed seems less clear and correct than the one in general use. Money, or the _value_ of the unit of money, is used as a measure in comparing the values of other things just as a yardstick, or the _length_ of a yard, is used in comparing the lengths of other objects. Money, in acting as a medium of exchange, must also act as a store of value to some extent, since it stores the value received until it is expended; but the use of money for the purpose of hoarding is not to be regarded as strictly one of its functions, at least not in the sense of requiring to be especially provided for. The fact that it is so used, however, should be borne in mind, as it interferes more or less with its other and more important functions; but in considering the qualities necessary to the best performance of the functions of money we may omit this last function, as any money which fills the requirements for the others will fulfil those necessary to this in a sufficient degree considering its minor importance. As our inquiries in this work will be confined to the money materials now in general use, viz., gold, silver, and paper, we need not consider the qualities necessary to a money material, as given by Professor Jevons,--such as portability, indestructibility, divisibility, etc.,--further than to say that the qualities he mentions are possessed by all of the money materials now in use, in a sufficient and nearly equal degree. Coin, to be sure, is more indestructible than paper; but as the paper is sufficiently acceptable for the purpose, the difference need not concern us.