The Nature and Growth of Capital
Marx defines capital as the extracted raw material, manufacture of labor instruments, and production of means of subsistence to create new raw materials, new labor instruments, new means of subsistence. An example of capital could be this: a rubber farm harvests rubber and sells it to a tire factory. The rubber farm would be an extraction of raw material, and the tire factory would be manufacturing new raw materials to sell to automobile companies.
Marx also calls capital “accumulated labor.” Production requires specific and reciprocal social relations. E.g., if there is no crude oil, there are no jobs to make cars, or refining plants to make gasoline, or truckers to transport it—and all the communities that form around these sectors become less tied, less communal. Marx contends that social relations vary and alter according to the means of production. Each epoch of the means of production becomes discrete: ancient, feudal, capitalist.
Capitalism is a bourgeois social relation. It operates under the assumption of exploiting a class that can only work, but without possession of property. Elsewhere, Marx equates property with capital. E.g., the worker doesn’t control the property that manufactures iPhones, the property from which they extract rare minerals, the seed patent property of Monsanto, the utility property that heats and cools their homes, water treatment property, or the property of bus and train systems. In the end, capital is living labor serving accumulated labor: preserving and multiplying it; it does not serve the living, except the bourgeois.
Relation of Wage-labor to Capital
In the relation between wage-labor and capital, the former gains subsistence, though this subsistence is consumed immediately for life. The latter receives even more value added to accumulated labor. Marx uses the example of the day laborer getting paid $1 a day, even though he produced $2 of product. This extra $1 of value he produced goes to the capitalist, $1 of value he didn’t work for. Multiply this by 5 workers, 20 workers, 100 workers, 1000 workers. This is that much money the capitalist gains for all the work produced by the laborer(s), again that he didn’t work for.
An increase in capital requires an increase in workers, because it requires that much more labor to increase it. As it grows, living labor more and more serves accumulated labor, both of the accumulated labor of their own making and that which past workers have produced. The capital remains long after workers are dead. Consider the Rockefeller family. The Rockefeller progeny still lives off of the formerly exploited labor of 19th-century workers, while continuing to add more to that accumulation through exploitation of 20th- and 21st-century laborers. Workers perish without work; capital perishes without exploitation.