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 Cyclopaedia defines money in the following words:

Anything which freely circulates from hand to hand, in any
country, as a common, acceptable medium of exchange, i