Marx had a special concern with how people relate to their own labour power. He wrote extensively about this in terms of the problem of alienation. As with the dialectic, Marx began with a Hegelian notion of alienation but developed a more materialist conception. Capitalism mediates social relationships of production (such as among workers or between workers and capitalists) through commodities, including labour, that are bought and sold on the market. For Marx, the possibility that one may give up ownership of one's own labour – one's capacity to transform the world – is tantamount to being alienated from one's own nature and it is a spiritual loss. Marx described this loss as commodity fetishism, in which the things that people produce, commodities, appear to have a life and movement of their own to which humans and their behaviour merely adapt.