In a similar way it can be shown that the _effective_ utility of a product A produced by the first hour of labor is the same as the actual utility of the product B produced by the tenth hour. For if A were to be lost, destroyed, or traded away, another A could be produced in its stead through the sacrifice of a B, by turning the tenth hour from B to the production of an A. In effect, then, upon the possession of A is _dependent_ merely the utility of B. The utility of a good is defined as its power to afford satisfaction, but the “effective utility” of a good as conceived by Professor Clark is, we may say, the power of that good over a man’s satisfactions, taking into consideration the adjustments he may make in his productive activities in case of the loss of that good. If he produces this same good over again, and instead goes without some other good, _in effect_ he foregoes the utility of the latter, and this is precisely the _effective utility_ of the first good.[237] Thus, in Professor Clark’s view, the utility produced by the last increment of a man’s labor affords a unit for measuring the effective utility to him of any and all the freely producible products of his labor. But it has already been shown that the _disutility_ of this last increment of labor is equal to the utility produced by it. Thus terminal disutility becomes also an available unit of “subjective” or esteem value, and Professor Clark adopts this as the “ultimate standard of value” upon the ground that pain is a more convenient measure than pleasure.[238] The theory signifies that the subjective value to the isolated producer of any good whose supply depends on labor can be most conveniently measured by the labor cost of that good. To quote: It follows that, in the case of an isolated man, we may measure the subjective value of goods by the mere duration of the work that creates them. All goods made in an hour are equal in effective utility and all hours of labor are of equal effective disutility. Destroy the product of an hour’s work, and you injure the man by a fixed amount; make any hour’s work unnecessary, by making nature freely supply what is produced in that period, and you benefit the man by a fixed amount.... The product of two hours’ work will always be of just twice as much subjective value as is the product of one.[239]