188 MODERN MONETARY SYSTEMS
Moreover, even with a normal monetary system, when
the exchanges are stable and there is no increase in the
volume of currency capable of destroying the balance be-
tween the supply and demand of commodities, prices will
still vary with the technique of production. Hence the
number of monetary units corresponding to a given quan-
tity of commodities will necessarily vary from one period
to another. Therefore we should not hold z priori that a
sum of money at one period will be equivalent to the same
sum of money at another period. In order to carry out
transactions which are spread over a period of time, we
ought logically to ascertain this equivalence with the help
of coefficients. And it is money—a bad “accumulator” of
value but an exact measure of changes of value—which
will enable us to determine those coefficients.
§ 2. Anempis to find a legal solution for the problem of un-
stable currency.
Thus the problem appears to be much more legal than
economic in character and it seems that it ought to be
solved by the way of drawing up contracts.
Taking first long-term contracts, for instance long-term
leases, a normal solution would be to fix a rent varying
with the average level of retail prices—as set up, for in-
stance, in France in the general statistics—in the year or
half-year preceding the date when it falls due; such statis-
tical data would make it possible to fix, on every date when
the rent falls due, as nearly as possible a sum representing
the purchasing power of the currency which was provided
for when the contract was concluded.
We see the same idea applied in countries with highly
depreciated currencies in gold loans, which often do not
involve payment of the sums lent nor the sums reimbursed
plus interest in gold valuta, but merely the payment in
internal currency of a sum X, which corresponds at the
date when each operation is effected to a given value fixed
in gold. This system, which is based theoretically on gold
and in practice on some foreign currency such as the
