The same dollar may, by passing from hand to hand, make a number of purchases, and the same goods may be sold repeatedly before consumption. It is, probably, correct to say, that the money available for use multiplied by the rapidity of circulation, or, as Mr. Mill expresses it, by its efficiency, equals the total money to be considered; and the commodities sold multiplied by the average number of sales equals the total commodities to be taken into consideration in fixing the general level of prices. Are there any other elements that act on the general level of prices? Of course an abundant yield, or a short crop, or an over-production, so called, or under-consumption, of any particular commodity may depress or raise the price of that particular crop or commodity; but are there any elements other than those above enumerated that act on the general level of prices? I think there are none. If, then, prices are controlled by the volume of money available for use; and if the general level of prices will rise as the volume of money is increased, and fall as the volume of money is diminished, and rise or fall in an exact ratio corresponding with the expansion or contraction of the volume of money, it becomes important to ascertain what money is, and also whether there is anything which can be used as a substitute for money in such a manner as to affect the general level of prices. Senator John P. Jones, than whom there is no one better informed, says: The money of a country is that thing, whatever it may be, which is commonly accepted in exchange for labor or property and in payment of debt, whether so accepted by force of law or by universal consent. Its value does not arise from the intrinsic qualities which the material of which it is made may possess, but depends entirely on extrinsic qualities which law or common consent may confer. Aristotle says: Money has value only by law and not by nature; so that a change of convention between those who use it is sufficient to deprive it of its value and power to satisfy our wants. Adam Smith says: A guinea may be considered a bill for a certain quantity of goods on all the tradesmen in the neighborhood. Henry Thornton says: Money of every kind is an order for goods. It is so considered by the laborer when he receives it, and it is almost instantly converted into money's worth. It is merely the instrument by which the purchasable stock of the country is distributed with convenience and advantage among the several members of the community. John Stuart Mill says: The pounds or shillings which a man receives are a sort of ticket or order which he may present for payment at any shop he pleases, and which entitles him to receive a certain value of any commodity that he may choose. Appleton's Cyclopædia defines money in the following words: