Use-values are primarily means of existence. These means of existence, however, are themselves products of social life, the result of expended human vital power, materialized labor. As the embodiment of social labor, all commodities are the crystallization of the same substance. Let us now consider the nature of this substance, i. e., of labor, which is expressed in exchange value.
Let one ounce of gold, one ton of iron, one quarter of wheat and twenty yards of silk represent equal exchange values. As equivalents, in which the qualitative difference between their use-values has been eliminated, they represent equal volumes of the same kind of labor. The labor which is equally embodied in all of them must be uniform, homogeneous, simple labor. It matters as little in the case of labor whether it be embodied in gold, iron, wheat, or silk, as it does in the case of oxygen, whether it appears in the rust of iron, in the atmosphere, in the juice of a grape, or in the blood of a human being. But the digging of gold, the extraction of iron from a mine, the raising of wheat and the weaving of silk are so many kinds of labor, differing in quality. As a matter of fact, what in reality appears as a difference in use-values, is in the process of production, a difference in the work creating those use-values. Just as labor, which creates exchange value, is indifferent to the material of use-values, so it is to the special form of labor itself. Furthermore, the different use-values are the products of the work of different individuals, consequently the result of various kinds of labor differing individually
