"It must be acknowledged that our worker emerges from the process of production looking different from when he entered it. In the market, as owner of the commodity 'labour-power', he stood face to face with other owners of commodities, one owner against another owner. The contract by which he sold his labour-power to the capitalist proved in black and white, so to speak, that he was free to dispose of himself. But when the transaction was concluded, it was discovered that he was no 'free agent', that the period of time for which he is free to sell his labour-power is the period of time for which he forced to sell it, that in fact the vampire will not let go 'while there remains a single muscle, sinew or drop of blood to be exploited'."