With the rise of the giant corporations, the wave of trustification and monopolization as well as the key role of class struggle in the production and distribution of surplus value, capitalism has undergone some major changes since the 1870s. The desire to justify the deep-seated irrationality of the monopoly capitalism increasingly leads to a new kind of fetishization and rationalization as the contradiction between the productive forces and relations of production intensifies. Economics has turned rapidly into apologetics for a more and more retrograde social and economic order. The sales effort develops from an auxiliary of the production process into an integral and indeed decisively important part of it at the phase of monopoly capitalism. The interpenetration of production and sales becomes one of the typical features of monopoly capitalism. The value of labor power becomes a flexible quantity susceptible to significant variations. Monopolistic profits can be earned under such circumstances not merely by the monopolists’ redistributing the aggregate surplus value in their favor, but by means of a price policy that reduces the real wages of labor. The distribution of net domestic production between surplus value and wages depends not only on the production process but also on the circulation process. To understand the laws of economic movement of monopoly capitalism, it is necessary not only to return to Marxist political economy, but also to use the concept of economic surplus to explain the new changes in contemporary capitalism.