Capital, Volume Three: The Process of Capitalist Production as a Whole by Karl Marx

I. General

We have seen in the first part of this book that the rate of profit expresses the rate of surplus-value always lower than it actually is. We have just seen that even a rising rate of surplus-value has a tendency to express itself in a falling rate of profit. The rate of profit would equal the rate of surplus-value only if c = 0, i.e. , if the total capital were paid out in wages. A falling rate of profit does not express a falling rate of surplus-value, unless the proportion of the value of the constant capital to the quantity of labour-power which sets it in motion remains unchanged or the amount of labour-power increases in relation to the value of the constant capital.