That is, capital is the expression of a specific social relation of labor. Capital is the congealment of abstract, undifferentiated labor. Capitalism reduces all concrete labor to its opposite-to abstract, undifferentiated labor. It is often said that labor is the source of all value. That is, only that which is the product of abstract labor has value in capitalism.
Capital is a social relation of abstract labor.
As the repository of surplus value, capital is driven to constantly go beyond itself, irrespective of natural or human-imposed limits. Herein lies the secret of capital's enormous productivity as well as its destructiveness. Capital is the endless and limitless drive to go beyond its limiting barrier. Every boundary is and has to be a barrier for it. For this reason any effort to control capital without uprooting the basis of value production is ultimately self-defeating.