[...] the concept of exploitation was fundamental. Exploitation is the extraction of surplus-value – that is, the portion of labour performed by wage-labourers for which they are not remunerated by capitalists. It is an economic concept, even if its consequences extend far beyond this sphere as traditionally conceived. This notion, like the representation of the social world that goes with it, tends to assign centrality to economic oppression – that suffered by the industrial working class – and to regard other forms of oppression, like male domination or colonialism, as secondary. This is what Marxists once called the problematic of ‘secondary fronts’, the ‘main’ front being the opposition between capital and labour. Contrary to a current but erroneous retrospective view, ‘qualitative’ themes – this is an important point – were never absent from Marxism and the labour movement. But in it exploitation nevertheless played the role of organizing concept.