Karl Marx
Wage Labour and Capital
In the process of production, human beings work not only upon nature, but also upon one another. They produce only by working together in a specified manner and reciprocally exchanging their activities. In order to produce, they enter into definite connections and relations to one another, and only within these social connections and relations does their influence upon nature operate — i.e., does production take place.
These social relations between the producers, and the conditions under which they exchange their activities and share in the total act of production, will naturally vary according to the character of the means of production. With the discovery of a new instrument of warfare, the firearm, the whole internal organization of the army was necessarily altered, the relations within which individuals compose an army and can work as an army were transformed, and the relation of different armies to another was likewise changed.
We thus see that the social relations within which individuals produce, the social relations of production, are altered, transformed, with the change and development of the material means of production, of the forces of production. The relations of production in their totality constitute what is called the social relations, society, and, moreover, a society at a definite stage of historical development, a society with peculiar, distinctive characteristics. Ancient society, feudal society, bourgeois (or capitalist) society, are such totalities of relations of production, each of which denotes a particular stage of development in the history of mankind.
Capital also is a social relation of production. It is a bourgeois relation of production , a relation of production of bourgeois society. The means of subsistence, the instruments of labor, the raw materials, of which capital consists — have they not been produced and accumulated under given social conditions, within definite special relations? Are they not employed for new production, under given special conditions, within definite social relations? And does not just the definite social character stamp the products which serve for new production as capital?
Online Version: Marx/Engels Selected Works (marxists.org) 1999
Abstract by: Historical Materialism (Marx, Engels, Lenin); p. 103-104
Original text: Chapter Five of Wage Labour and Capital