What is now the course of the production of the surplus-value? The capitalist has fitted up a factory, has procured tools and raw material, has hired labor, and the process of production commences. Suppose that the necessaries of life for the workman and his family may be produced by six hours of work socially necessary; by making him work, then, six hours the capitalist will have a product equal to that of the raw material used, increased by that which is given it by the tools and by the labor which the workman has put upon it. This value, however, has been entirely paid out by the capitalist; he has no surplus left; the transaction has failed. But ordinarily the process succeeds in procuring profits for the capitalist, since in the contract between him and the laborer it is not stipulated that the latter shall work only the number of hours necessary to produce enough for his own needs. On the contrary the workman is compelled to labor as long as his strength will permit. The value produced by the workman after the time necessary for the production of the equivalent of his needs falls to the capitalist, and this it is which constitutes the surplus-value, the value derived from work not paid for. The aim of the capitalist is to procure for himself as large a surplus-value as possible. He can attain his end at once by forcing the laborer to work as long a time as it is possible for him to work. From this springs the irreconcilable conflict between the interests of the proletariat and those of capital, the combat over the length of the working-day. The day has its natural limits (it is necessary that certain hours be left to the workman for food and rest), its legal limits (decreed too late by the state, driven on one side by the workers themselves, and on the other by the plain certainty that without this protection the working class would become enfeebled), and finally its limits fixed by the pressure of the labor unions. However, there is still one other way in which the surplus-value is increased, as I shall explain by what follows. Let us suppose the length of the working day to be twelve hours, and the time necessary for the production of the equivalent of the workman’s needs to be six hours. We can then represent the day as follows: A----|----|----|----|----|----|----|----|----|----|----|----B C