THE PROBLEM OF INTEREST 81

therefore, be anticipated demand for those consumable
goods, combined with knowledge as to the efficiency of
the instruments in producing them, that leads to the demand
for the instruments. The correction of inaccurate estimates
of the demand for the commodities can only result from
experience, and hence we may expect that the adjustment
of supplies to demand, at any rate to demand at the anticipated
 level of value, will be less prompt than in the case
of commodities whose preparation needs little preliminary
provision of materials and instruments of production.
Investments of capital, that is to say the giving to capital
of specific instrumental forms, are made on the basis of
anticipation of future conditions. The change of the forms
of capital can only be effected slowly. Hence we might
reasonably expect a considerable lack of adjustment, between
the forms, and the total amount, of capital and the demand
for that capital arising out of the productive services it
can render. The actual utility of existing capital, like the
marginal utility of a given fixed quantity of a particular
consumable commodity, is a result of actual existing
conditions. The supply of capital, both as a whole, and
in the various forms it may assume, may be either greater
or less than would be worth producing in order to secure
the value represented by actual marginal utilities.
Capital which exists as a particular instrument of production,
 whether materials, buildings, machinery, or other form,
be in question, has a marginal utility which depends on the
actual supply of that particular instrument in relation to the
demand for the services it can render. The increase or
decrease of the supply results from the relation of this
marginal utility to the cost of production, modified by
anticipations as to the changes which the marginal utility
may undergo in the future, The more enduring the form
of the particular instrument, the more remote the influence
on its value of possible or probable changes in its supply
stimulated by this relation of utility to cost of production.
In dealing with the question of the value of capital, and
with this as a particular application of the general principles
of value as dependent on demand and supply, we are