day because he cannot work longer and work permanently and well, and he gets three shillings a day of wages, because three shillings will buy him the necessities he requires. In six hours' labour he will create three shillings' worth of value, and he works the other six hours for nothing, creating three shillings' worth of surplus value for the master who advances him his wages. It is from these causes that we come on the present system of things to the singular result that powers of labour which create six shillings a day are themselves worth only three shillings a day. This absurd conclusion, says Marx, could never have held ground for an hour, had it not been hid and disguised by the practice of paying wages in money. This makes it seem as if the labourer were paid for the whole day when he is only paid for the half. Under the old system of feudal servitude there were no such disguises. The labourer wrought for his master one day, and for himself the other five, and there was no make-believe as if he were working for himself all the time. But the wages system gives to surplus labour that is really unpaid the false appearance of being paid. That is the mystery of iniquity of the whole system, the source of all prevailing legal conceptions of the relation of employer and employed, and of all the illusions about industrial freedom. The wages system is the lever of the labourer's exploitation, because it enables the capitalist to appropriate the entire surplus value created by the labourer--_i.e._, the value he creates over and above what is necessary to recruit his labouring powers withal. Now surplus value, as we have seen, is of two kinds, absolute and relative. Absolute surplus value is got by lengthening the term of surplus labour; relative surplus value by shortening the term of necessary labour, which is chiefly done by inventions that cheapen the necessaries of life. The consideration of the first of these points leads Marx into a discussion of the normal length of the day of labour; and the consideration of the second into a discussion of the effects of inventions and machinery on the condition of the working classes. We shall follow him on these points in their order.