The labour employed here is more productive, its individual productive power is greater than that employed in the majority of factories of the same kind. Its greater productive power is shown in the fact that in order to produce the same quantity of commodities, it requires a smaller quantity of constant capital, a smaller quantity of materialised labour, than the others. It also requires less living labour, because the water-wheel need not be heated. This greater individual productiveness of employed labour reduces the value, but also the cost-price and thereby the price of production of the commodity. For the individual industrial capitalist this expresses itself in a lower cost-price for his commodities. He has to pay for less materialised labour, and also less wages for less living labour-power employed. Since the cost-price of his commodities is lower, his individual price of production is also lower. His cost-price is 90 instead of 100. His individual price of production would therefore be only 103½ instead of 115 (100:115 = 90:103½) The difference between his individual price of production and the general price of production is limited by the difference between his individual cost- price and the general cost-price. This is one of the magnitudes which form the limits to his surplus-profit. The other is the magnitude of the general price of production into which the general rate of profit enters as one of the regulating factors. Were coal to become cheaper, the difference between his individual cost-price and the general cost-price would decrease, and with it his surplus-profit. Should he be compelled to sell his commodities at their individual value, or at the price of production determined by their individual value, then the difference would disappear. It is, on the one hand, a result of the fact that the commodities are sold at their general market-price, the price brought about by the equalisation of individual prices through competition, and, on the other, a result of the fact that the greater individual productivity of labour set in motion by him does not benefit the labourer, but the employer, as does all productivity of labour, that it appears as the productiveness of capital.