is he who possesses exclusive power over some
natural agent. The land is the principal natural agent capable of being
so appropriated, and the consideration paid for its use is called rent.

It is at once evident that rent is the effect of a monopoly. If all the
land of the country belonged to one person he could fix the rent at his
pleasure. The whole people would be dependent on his will for the
necessaries of life. But even when monopolised--in the sense of being
limited in quantity--land will command a price only if it exists in less
quantity than the demand, and no land ever pays rent unless, in point of
fertility and situation, it belongs to those superior kinds which exist
in less quantity than the demand.

Any land yields just so much more than the ordinary profits of stock as
it yields more than what is returned by the worst land in cultivation.
The surplus is what is paid as rent to the landlord. The standard of
rent, therefore, is the excess of the produce of any land beyond what
would be returned to the same capital if employed on the worst land in
cultivation, or, generally, in the least advantageous circumstances.

_III.--Of Exchange and Value_

Of the two great departments of political economy, the production of
wealth and its distribution, value has to do with the latter alone. The
conditions and laws of production would be unaltered if the arrangements
of society did not depend on, or admit of, exchange.

Value always means in political economy value in exchange, the command
which its possession gives over purchasable commodities in general;
whereas, by the price of a thing is understood its value in money.

That a thing may have value in exchange two conditions are necessary. It
must be of some use--that is, it must conduce to some purpose, and
secondly, there must be some difficulty in its attainment. This
difficulty is of three kinds. It may consist in an absolute limitation
of supply, as in the case of wines which can be grown only in peculiar
circumstances of soil, climate, and exposure; in the labour and expense
requisite to produce the commodity; or, thirdly, the limitation of the
quantity which can be produced at a given cost, to which class
agricultural produce belongs, increased production beyond a certain
limit entailing increased cost.

When the production of a commodity is the effect of labour and
expenditure, there is a minimum value, which is the essential condition
of its perman