[88 ON THE CAUSES

hand compelled by his own interest to bring to
market the whole of his supply, and he is
obliged by the same principle to produce the
greatest supply in his power, so long as the
average price pays him a higher profit than the
ordinary employment of capital. It deserves
to be remarked, that all commodities, which re-
quire any considerable period of time for their
production, are liable to be occasionally forced
into the class of articles owing their value to
this second kind of monopoly, by a sudden
alteration in the relative state of the demand
and supply. Hence arises what is called by
political economists market value. Should the
relative demand for any of these commodities
increase, as it could not, according to the sup-
position, be immediately answered by a cor-
respondent supply, the possessors of the com-
modities would enjoy a: temporary monopoly ;
for a while they would be protected from com-
petition by the impossibility of producing a fur-
ther quantity.

On the contrary, should the relative demand