178 A MEASURE AND A CAUSE OF VALUE. 
tion of 2 commodity in which a definite por- 
tion of it was embodied *. 
All that is really meant by a measure of 
value we have already seen, and what is im- 
plied by a cause of value will be examined in 
the following chapter. The object of the pre- 
ceding brief discussion is not to consider the 
nature of either, but merely to show the es- 
sential distinction between the ideas which they 
involve. 
* There was a further reason, namely, that the real object 
which he contemplated in a measure of value was to ascer- 
tain by it the changes which commodities wight undergo 
in regard to the quantity of labour required to produce 
them. Now to use labour itself as a measure implies this 
object to be already accomplished. Sce Note I.