92 ON COMPARING COMMODITIES

In this chapter I beg not to be understood as
contending, either that the values of commodities
 are to each other as the quantities of labour
necessary for their production, or that the
values of commodities are to each other as the
values of the labour: all that I intend to insist
upon is, that if the former is true, the latter
cannot be false ; and I have endeavoured to explain
 the source of the misconception which
has regarded the two propositions as incompatible
 and contradictory *. The fact is, that the
quantity of labour and the value of labour are in
the same case. Any alteration in the comparative
 quantities of labour required to produce a
and B, would alter their value in relation to
gach other; and an alteration in their mutual
value would equally follow from any change in
the comparative values of the producing labour,

* Of the two propositions, however, the latter is a much
nearer approximation to the truth, for reasons which will
be stated in a subsequent chapter on the causes of value.