92 ON COMPARING COMMODITIES 
In this chapter I beg not to be understood as 
contending, either that the values of commodi- 
ties 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 ex- 
plain the source of the misconception which 
has regarded the two propositions as incompa- 
tible and contradictory *. The fact is, that the 
quantity of labour and the value of labour are in 
the same case. Any alteration in the compara- 
tive 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.