In the preceding part we demonstrated, among other things, that the rate of
 profit may vary — rise or fall — while the rate of surplus-value
 remains the same. In the present chapter we assume that the intensity of labor
 exploitation, and therefore the rate of surplus-value and the length of the
 working-day, are the same in all the spheres of production into which the
 social labor of a given country is divided. Adam Smith has already
 comprehensively shown that the numerous differences in the exploitation of
 labor in various spheres of production balance one another by means of all
 kinds of existing compensations, or compensations accepted as such on the basis
 of current prejudice, so that they are merely evanescent distinctions and are
 of no moment in a study of the general relations. Other differences, for
 instance those in the wage scale, rest largely on the difference between simple
 and complicated labor mentioned in the beginning of Book I (p. 19), and have
 nothing to do with the intensity of exploitation in the different spheres of
 production, although they render the lot of the laborer in those spheres very
 unequal. For instance, if the labor of a goldsmith is better paid than that of
 a day-laborer, the former's surplus-labor produces proportionately more
 surplus-value than the latter's. And although the equalizing of wages and
 working-days, and thereby of the rates of surplus-value, among different
 spheres of production, and even among different investments of capital in the
 same sphere of production, is checked by all kinds of local obstacles, it is
 nevertheless taking place more and more with the advance of capitalist
 production and the subordination of all economic conditions to this mode of
 production. The study of such frictions, while important to any special work on
 wages, may be dispensed with as incidental and irrelevant in a general analysis
 of capitalist production. In a general analysis of this kind it is usually
 always assumed that the actual conditions correspond to their conception, or,
 what is the same, that actual conditions are represented only to the extent
 that they are typical of their own general case.