Report, if you have a problem with this page“ This false appearance distinguishes wages labour from other historical forms of labour. On the basis of the wages system even the unpaid labour seems to be paid labour. With the slave, on the contrary, even that part of his labour which is paid appears to be unpaid. Of course, in order to work the slave must live, and one part of his working day goes to replace the value of his own maintenance. But since no bargain is struck between him and his master, and no acts of selling and buying are going on between the two parties, all his labour seems to be given away for nothing. ”
Karl Marx
From : Wage-Labour and Capital/Value
