228 ON THE CAUSES

restrict his inquiries to “ such commodities only
as can be increased in quantity by the exertion
of human industry, and on the production of
which competition operates without restraint.”
Instead, however, of confining himself to these
commodities, he enters into the consideration
of the value of labour, of com, of gold, and
of other articles, in the production of which
competition certainly does not operate without
restraint ; but which he is obliged to bring under
 that head, from the imperfect classification
with which he sets out. According to his own
division, the value of these things should be
determined by the quantity of labour necessary
to produce them: but of none of them can
this be asserted ; for the value of labour can in
no sense be said to be determined by the quantity
 of labour necessary to produce it: the
value of corn in general is determined, on
his own principles, by the quantity of labour
required to raise corn on the worst soils in
cultivation, and not by the quantity of its own
producing labour; and in the same way the