or which the two terms stand are
by no means identical, and that effective utility must be
studied in any complete analysis of value. In distinguishing
final utility we assume that the units of the supply of goods
of a particular kind are furnished one by one, and we measure
the absolute utility of each unit. The line _AB_ measures the
_absolute_ utility of the first unit supplied. This
measurement does not take any account of the cost of
replacing this unit, for it does not recognize the
possibility of replacing it. What is estimated is the
absolute importance of the service which this first unit of
the article renders, on the supposition that, if this first
increment of the supply were wanting, the service would not
be rendered at all. It is, in like manner, the absolute
utility of the successive increments supplied which declines
along the curve _BC_. _DC_ measures the _absolute_ utility of
the final increment, and the area _ABCD_ the total absolute
utility of the supply. If the goods can be reproduced by
labor, the total effective utility is less, since it is
measured, as we have seen, by the amount of sacrifice which
the replacing of one lost unit would entail multiplied by the
number of units in the supply. It is the amount expressed by
the area _AECD_ which is the amount of the value of the
goods, since measure of effective utility and value are the
same, both in the case of a single unit and in that of a
total supply.

We have discovered two reasons why the effective utility of
any one of the earlier units is equal to the absolute utility
of the final one. The first reason is that, if any one of
them were lost, the final one would be put in the place of it
and the consumer would suffer no loss except what would be
entailed by going without the last unit. The second reason is
that if the consumer should lose any one of the earlier
units, he could replace it by the same amount of labor that
would replace the final one. We have seen that the line _DC_
of the figure expresses not only the absolute utility of the
final unit of goods, but the disutility of the labor of
reproducing it or of reproducing any other unit. The cost of
replacing the whole supply is expressed by the area _AECD_,
on the supposition that the units are replaced, one at a
time, by mean