One principal theme in the work of Émile Durkheim concerns the sources of moral and therefore social order in society. In particular, Durkheim was concerned to elaborate the connection between the individual and society, in a time of growing individualism, social dislocation, and moral diversification. In his famous treatise on The Division of Labour in Society (1893) he juxtaposed the solidarity of resemblance, characteristic of segmented, opaque societies where ‘mechanical solidarity’ prevailed, to the solidarity of occupational interdependence in morally dense societies characterized by ‘organic solidarity’. The transition from one to the other was neither obvious nor inevitable—as he was the first to admit in his afterwords on abnormal forms of the division of labour. In subsequent writings, Durkheim sought to make suggestions as to the institutional solutions to the problems of moral regulation and social integration in contemporary societies, in particular suggesting the importance of the ‘occupational association’ (a sort of modern equivalent of the medieval guild) as a mediator between the individual and society. In the Elementary Forms of Religious Life (1912), social solidarity—society—was found to be the very object of collective worship.