Labor, which creates exchange value, is, finally, characterized by the fact that even the social relations of men appear in the reversed form of a social relation of things. Only in so far as two use-values are in a mutual relation of exchange values does the labor of different persons possess the common property of being identical universal labor. Hence, if it be correct to say that exchange value is a relation between persons,[5] it must be added that it is a relation disguised under a material cover. Just as a pound of iron and a pound of gold represent the _same_ weight in spite of their different physical and chemical properties, so do two use-values, as commodities containing the same quantity of labor-time, represent the _same exchange value_. Exchange value thus appears as the natural social destination of use-values, a property which they possess by virtue of being things and in consequence of which they are exchanged for one another in definite proportions, or form equivalents, just as chemical elements combine in certain proportions, forming chemical equivalents. It is only through the habit of everyday life that we come to think it perfectly plain and commonplace, that a social relation of production should take on the form of a thing, so that the relation of persons in their work appears in the form of a mutual relation between things, and between things and persons. In commodities this mystification is as yet very simple. It is more or less plain to everybody that a relation of commodities as exchange values is nothing but a mutual relation between persons in their productive activity. This semblance of simplicity disappears in higher productive relations. All the illusions in regard to the monetary system are due to the fact that money is not regarded as something representing a social relation of production, but as a product of nature endowed with certain properties. The modern economists who sneer at the illusions of the monetary system, betray the same illusion as soon as they have to deal with higher economic forms, as, e. g., capital.[6] It breaks forth in their confession of naive surprise, when what they have just thought to have defined with great difficulty as a thing suddenly appears as a social relation and then reappears to tease them again as a thing, before they have barely managed to define it as a social relation.