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ON MEASURES 
confounded two perfectly distinct ideas, name- 
ly, measuring the value of commodities, and 
ascertaining in which commodity, and in what 
degree, the causes of value have varied. 
For suppose we had such a commodity as he 
requires for a standard : suppose, for instance, 
all commodities to be produced by labour 
alone, and silver to be produced by an invari- 
able quantity of labour. In this case silver 
would be, according to Mr. Ricardo, a perfect 
measure of value.” But in what sense? What 
is the function performed? Silver, even if in- 
variable in its producing labour, will tell us 
nothing of the value of other commodities. 
Their relations in value to silver, or their prices, 
must be ascertained in the usual way, and 
when ascertained, we shall certainly know the 
values of commodities in relation to each other : 
but in all this there is no assistance derived 
from the circumstance of the producing labour 
of silver being a constant quantity. 
But it is the fluctuations of commodities 
which this invariable standard is to ascertain or