What is this thing we have called wage-labour, about which we have theorized? Clearly, it is that which stands opposite to capital within capitalism. Wage-labour is the necessary mediator for capital in capital's thrust to grow. The reproduction of capital requires the reproduction of a body of wage-labourers, a mass of human instruments of production who must enter into a relation in which they perform surplus labour for capital. Thus, wage-labour is a necessary moment within the reproduction of capital.