In possessing exchange value relative to one another, commodities show their unique characteristic. It is only as commodities, in a society where exc… - Paul Sweezy

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.

It must be emphasized, because the contrary has so often been asserted, that Marx was not trying to reduce everything to economic terms. He was rather attempting to uncover the true interrelation between the economic and the non-economic factors in the totality of social existence.

In possessing use value a commodity is in no way peculiar. Objects of human consumption in every age and in every form of society likewise possess use value. Use value is an expression of a certain relation between the consumer and the object consumed. Political economy, on the other hand, is a social science of the relations between people.