OF VALUE.

115

would result from the supposed want of a com-
mon instrument for measuring space.

It is obvious then, that if no relation of
value can exist between objects in different
ages, there can be no measurement of it, nor
consequently can there be any measure or me-
dium of comparison required.

The only thing to be done, with regard to
different periods, is to compare the relation of
value subsisting between any two commodities,
A and B, at one period, with the relation subsist-
ing between them at another; or, in other
words, the quantity of a which purchased B at
the former time, with the quantity of A which
purchased B at the latter. This is evidently a
simple comparison, in which neither 4 nor B
perform the function of a measure, or medium,
in any possible interpretation of the term.
That office has in all likelihood been already
discharged in ascertaining the relative quanti-
ties of A and B at each period; and if, as is
probable, these quantities have been ascertained
by means of the prices of the commodities, money