146 ON THE MEASURE OF VALUE

of reasoning like this. Instead of proving labour
 to be of immutable value, it proves the reverse.
 An alteration in the mutual value of
two articles means, that the quantities in which
they are exchanged for each other are altered :
a definite quantity of one is exchanged for a
greater or smaller portion of the other than before.
 Now the only commodities in question,
in Mr. Malthus’s table, are corn and labour;
and if, as he supposes, the labour of 10 men is
at one time rewarded with 120 quarters of corn,
and at another time with only 80 quarters, the
only condition required for an alteration of
value is fulfilled, and labour, instead of being
invariable, has fallen one-third.
The fallacy lies in virtually considering or
speaking of wages, as if they were a commodity
 ; while, as the term is used by Mr. Malthus,
 it really implies an aggregate quantity of
corn, in the same way as the term sum implies
an aggregate quantity of money; and it is just
the same kind of futility to call wages invariable
in value, because though variable in quantity