supply the wants of their own family; then yarn and linen were _social_ products, spinning and weaving were _social_ labor within the limits of the family. But their social character did not manifest itself in the fact that yarn, as a universal equivalent, could be exchanged for linen as a universal equivalent, or that one was exchanged for another, as identical and equivalent expressions of the same universal labor-time. It was rather the family organization with its natural division of labor that impressed its peculiar social stamp on the product of labor. Or, let us take the services and payments in kind of the Middle Ages. It was the specific kind of labor performed by each individual in its natural form, the particular and not the universal aspect of labor, that constituted then the social tie. Or, let us finally take labor carried on in common in its primitive natural form, as we find it at the dawn of history of all civilized races.[4] It is clear that in this case labor does not acquire its social character from the fact that the labor of the individual takes on the abstract form of universal labor or that his product assumes the form of a universal equivalent. The very nature of production under a communal system makes it impossible for the labor of the individual to be private labor and his product to be a private product; on the contrary, it makes individual labor appear as the direct function of a member of a social organism. On the contrary, labor, which is expressed in exchange value, at once appears as the labor of a separate individual. It becomes social labor only by taking on the form of its direct opposite, the form of abstract universal labor.