28

ECONOMIC PRINCIPLES

served by that marginal supply. If we, then, take the series
of marginal-demand-prices corresponding to supplies of 1, 2,
3... units of commodity, and add them all together, the
sum may be taken to express the total services rendered by
the whole supply, though each and every unit is secured at a
sacrifice corresponding to the utility of the marginal, or final,
unit of the supply. The summation thus effected gives us a
measure of the total utility of the actual supply of the commodity.
 If, when in restricted supply, the commodity has
a large marginal utility, its total utility when in plentiful
supply will be correspondingly large, though its marginal
utility be then quite small. Our ordinary index of the
importance of a commodity is its price, which registers its
marginal utility. There is a consciousness that such an
index of the importance of very many commodities is
inadequate, and it is considered anomalous that some of the
things of greatest necessity bear very low prices. It is
suggested that this proves price to be an unsatisfactory
measure of utility, and that the word value is misapplied
when used in reference to the low price of goods of
inestimable importance. The consideration that it is the
total utility of a commodity which is the indication of its
importance to those who use it, while goods, some supply of
which is indispensable, may exist in such abundance that
a portion of that abundance can reasonably be applied to
unimportant purposes, and that the least important of the
purposes to which it is actually applied is the determinant of
what consumers are willing to give for it, may suffice to
explain the apparent anomaly.
In fact, when reference is made to the utility of a commodity,
 whether the term utility or value be used to denote
the quality, it is not generally the specific utility of some
particular part of the supply which is intended. No distinction
 is drawn between the utilities of different parts of
the supply in such a refererice. If we are informed as to the
quantity of commodity available, we can connect the value in
exchange with that particular grade in the diminishing scale
of utility which we have called the marginal utility. What
is the lowest grade of utility which secures satisfaction out of