, 
PREFACE. 
economist, is constantly employed, would sur- 
prise even the metaphysician, who is well aware 
of the extensive prevalence and unbounded in- 
fluence of the chameleon-like properties of 
language. No writer (as far as the author of the 
following pages is acquainted with works on 
economical science) has ever taken the trouble to 
analyse the meaning involved in the phrase. To 
measure value is an expression apparently so 
simple, so precise, so free from obscurity, that 
it seems superfluous to bestow a single inquiry 
on its import. The consequence has been 
what it generally proves on such occasions: 
the term has been used without any clear per- 
ception of a definite sense; several ideas 
have been unconsciously and indiscriminately 
interchanged, and analogies, which had merely 
an imaginary existence, have been assumed as 
incontrovertible premises or universally con- 
ceded postulates.