If it is further assumed that this gradual change in the composition of
 capital is not confined only to individual spheres of production, but that it
 occurs more or less in all, or at least in the key spheres of production, so
 that it involves changes in the average organic composition of the total
 capital of a certain society, then the gradual growth of constant capital in
 relation to variable capital must necessarily lead to a gradual fall of the
 general rate of profit, so long as the rate of surplus-value, or the
 intensity of exploitation of labour by capital, remain the same. Now we have
 seen that it is a law of capitalist production that its development is attended
 by a relative decrease of variable in relation to constant capital, and
 consequently to the total capital set in motion. This is just another way of
 saying that owing to the distinctive methods of production developing in the
 capitalist system the same number of labourers, i.e., the same
 quantity of labour-power set in motion by a variable capital of a given value,
 operate, work up and productively consume in the same time span an
 ever-increasing quantity of means of labour, machinery and fixed capital of all
 sorts, raw and auxiliary materials — and consequently a constant capital
 of an ever-increasing value. This continual relative decrease of the variable
 capital vis-a-vis the constant, and consequently the total capital, is
 identical with the progressively higher organic composition of the social
 capital in its average. It is likewise just another expression for the
 progressive development of the social productivity of labour, which is
 demonstrated precisely by the fact that the same number of labourers, in the
 same time, i.e., with less labour, convert an ever-increasing quantity
 of raw and auxiliary materials into products, thanks to the growing application
 of machinery and fixed capital in general. To this growing quantity of value of
 the constant capital — although indicating the growth of the real mass of
 use-values of which the constant capital materially consists only approximately
 — corresponds a progressive cheapening of products. Every individual
 product, considered by itself, contains a smaller quantity of labour than it
 did on a lower level of production, where the capital invested in wages
 occupies a far greater place compared to the capital invested in means of
 production. The hypothetical series drawn up at the beginning of this chapter
 expresses, therefore, the actual tendency of capitalist production. This mode
 of production produces a progressive relative decrease of the variable capital
 as compared to the constant capital, and consequently a continuously rising
 organic composition of the total capital. The immediate result of this is that
 the rate of surplus-value, at the same, or even a rising, degree of labour
 exploitation, is represented by a continually falling general rate of profit.
 (We shall see later [Present edition: Ch. XIV. — Ed.] why this
 fall does not manifest itself in an absolute form, but rather as a tendency
 toward a progressive fall.) The progressive tendency of the general rate of
 profit to fall is, therefore, just an expression peculiar to the capitalist
 mode of production of the progressive development of the social
 productivity of labour. This does not mean to say that the rate of profit may
 not fall temporarily for other reasons. But proceeding from the nature of the
 capitalist mode of production, it is thereby proved logical necessity that in
 its development the general average rate of surplus-value must express itself
 in a falling general rate of profit. Since the mass of the employed living
 labour is continually on the decline as compared to the mass of materialised
 labour set in motion by it, i.e., to the productively consumed means
 of production, it follows that the portion of living labour, unpaid and
 congealed in surplus-value, must also be continually on the decrease compared
 to the amount of value represented by the invested total capital. Since the
 ratio of the mass of surplus-value to the value of the invested total capital
 forms the rate of profit, this rate must constantly fall.