So far as the individual capitalists are concerned, each takes the wage level for granted and attempts to do the best he can for himself. In introduc… - Paul Sweezy

Supply and demand will be in equilibrium only when the price of every commodity is proportional to the labor time required to produce it. Conversely prices proportional to labor times will be established only if the forces of competitive supply and demand are allowed to work themselves out freely. The competitive supply-and-demand theory of price determination is hence not only not inconsistent with the labor theory; rather it forms an integral, if sometimes unrecognized, part of the labor theory.

In possessing exchange value relative to one another, commodities show their unique characteristic. It is only as commodities, in a society where exchange is a regular method of realizing the purpose of social production, that products have exchange value.

The magnitude of the rate of surplus value is directly determined by three factors: the length of the working day, the quantity of commodities entering into the real wage, and the productiveness of labor. The first establishes the total time to be divided between necessary and surplus labor, and the second and third together determine how much of this time is to be counted as necessary labor. Each of these three factors is in turn the focal point of a complex of forces which have to be analysed in the further development of the theory. The rate of surplus value may be raised either by an extension of the working day, or by a lowering of the real wage, or by an increase in the productiveness of labor, or, finally, by some combination of the three movements. In case of an increase in the length of the working day, Marx speaks of the production of absolute surplus value, while either a lowering of the real wage or an increase in productivity, leading to a reduction of necessary labor, results in the production of relative surplus value.