If we grant this conception of “real worth,” and the conception of a unit of disutility in general, distinguishable in the different labors of different persons, we still find difficulties ahead. The same commodity may exchange for two days of common labor or one day of skilled labor. Either of these is the quantity of labor commanded in exchange. According to Smith’s conception, either must measure its “real value.” Now the fact is, one day of skilled labor ordinarily involves _less disutility_ than two days of common labor.[43] Competitive wages are paid in proportion to _efficiency_, not in proportion to disutility. A given piece of labor will count as a great or small quantity when commanded in exchange in proportion to the wages paid for it. It is then a difficulty with Smith’s labor-command standard that he implies that labor derives its capacity to serve as a measure of real value from its disutility, while the same commodity will command _different_ disutilities in different exchanges. The attempt to reduce skill to disutility by urging that the higher wages of skill are in proportion to the disutility of acquiring the skill is futile. The tendency of the wages of skilled labor to proportion themselves to the comparative disutility of that labor—_i. e._, to the sum of the disutility daily felt plus some share or other of the past disutility cost of acquiring the skill—is so completely submerged beneath other forces that it is negligible. In addition to this, much skill is not acquired, but is inborn without having entailed any disutility cost of acquisition to its possessor. To conclude with this question, so far as Adam Smith means to suggest that the economic worth of a good to a given person can be measured _by him_ in terms of its disutility cost _to him_, the position and some of its consequences mentioned above are well taken. Smith’s theory, however, failed to penetrate the problem as do later theories of the final equivalence of utility and disutility. But the implications of his arguments further than this seem incapable of defense.