TO DISCOVER A STABLE STANDARD 185
But the fact that currency is a variable or unstable stan-
dard does not only follow from the mere statement that the
average price of commodities and therefore the purchasing
power of the currency has varied from one period to
another. We must try to define those cases in which,
having observed a variation in purchasing power, we may
attribute it to the currency. But it should be observed in
the first place that a standard of values is not in every
respect similar to any other standard of measure, and that
it cannot be used in the same way. It is true that a mone-
tary unit, like a unit of length, will enable us to determine
the relation between the said unit and any objects, and to
deduce therefrom the relation between the different objects.
A monetary unit makes it possible to determine variations
in the exchange value of a commodity in relation to that
unit itself, e.g., in the case of a hat, as between one date and
another, or the exchange ratio between a hat and an over-
coat at a given date, just as a unit of length will enable us to
demonstrate by how much a wall in process of building has
been raised between two different periods or to establish the
ratio existing at a given moment between the height of a
wall and the height of a tree. This kind of relation is given
by the franc just as well as by the metre; but there are
important differences between the nature of these two
standards. As M. Bourguin says : “When we measure the
length or the weight of some object by means of the metre
or the gramme, we are demonstrating a mere ratio be-
tween two lengths or weights which exist independently of
this ratio. The situation is quite different in the case of
money ; and if we say that a hectolitre of corn is worth 20
francs we are not comparing two ‘intrinsic’ values inde-
pendent of each other, we are setting up a ratio which is of
the essence of the idea of (exchange) value, since it is in
this ratio that value essentially resides.””? Indeed there is
reason to hold that the idea of exchange value corresponds
to that of a reciprocal measure, of a ratio of value, and does
not necessarily imply anything more. It will now be
1 “La mesure de la valeur et la monnaie,” Revue & économie politique,
1895, p. 235.
