Page:Contribution to the Critique of Political Economy, A - Karl Marx.djvu/29

Rh from one another. But as exchange values, they represent the same homogeneous labor, i. e., labor from which the individuality of the workers is eliminated. Labor creating exchange value is, therefore, abstract general labor. If one ounce of gold, one ton of iron, one quarter of wheat, and twenty yards of silk are exchange values of equal magnitude or equivalents; then one ounce of gold, half a ton of iron, three bushels of wheat and five yards of silk are exchange values of different magnitudes, and this quantitative difference is the only difference of which they are capable as exchange values. As exchange values of different magnitudes, they represent greater or smaller quantities of that simple, homogeneous, abstract, general labor, which forms the substance of exchange value. The question arises, how are these quantities to be measured? Or, rather what constitutes the substance of labor, which makes it capable of quantitative measurement, since the quantitative differences of commodities in their capacity of exchange values are but quantitative differences of labor embodied in them. Just as motion is measured by time, so is labor measured by labor-time. Given the quality of labor, the difference in its duration is the only property by which it can be distinguished. As labor-time, labor has the same standard of measurement as the natural time measures, viz., hours, days, weeks, etc. Labor-time is the vital substance of labor, independent of its form, composition, individuality; it is its vital substance quantitatively, having at the same time its own inherent measure. Labor-time embodied in the