On this assumption we have seen that the relative magnitudes of surplus value and of price of labour power are determined by three circumstances; the length of the working day, or the extensive magnitude of labour; the normal intensity of labour, its intensive magnitude, whereby a given quantity of labour is expended in a given time; the productiveness of labour,whereby the same quantum of labour yields, in a given time, a greater or less quantum of product, dependent on the degree of development in the conditions of production.