rr 
rN 
ON MEASURES 
but we shall never be able by such means to 
discover the relation of value existing between 
them. We shall never extort from them a sin- 
gle fact with which we were before unac- 
quainted. What then is it possible to do in the 
way of measuring value? What kind of measure- 
ment is intended, when the term is so frequently 
employed? All that is practicable appears to 
be simply this : if I know the value of A in rela- 
tion to B, and the value of B in relation to c, 1 
can tell the value of A and c¢ in relation to each 
other, and consequently their comparative power 
in purchasing all other commodities. This is 
an operation obviously bearing no resemblance 
at all to the process of measuring length. There 
is no unknown fact discovered by a physical 
operation: itis in truth a calculation from cer- 
tain data, a mere question in arithmetic. It is 
not, let it be observed, what on a first glance 
it may appear, like ascertaining the compara- 
tive length of two pieces of timber which can- 
not be brought into juxta-position, by means of 
a foot rule or other instrument which we apply