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: