Although we may use the terms _final utility_ and _effective utility_ in a way that makes them nearly interchangeable, it is clear that the qualities for 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.