 Theories of practice were discussed in  section 3.2.4,  as theories of the constituents or parts of social phenomena. Dances, for instance, involve physical and mental routines: among the constituents of a cha-cha are people’s thoughts and actions on the dance floor. However, theories of practice are not so easily categorized. Particular tokens of dance routines might be understood as playing a dual role: not only are they the constituents of cha-chas, but they also are among the sources of the category cha-cha. In this respect, theories of practice share an insight with certain “pattern” theories (see sections  4.3.2  and  4.3.3):  the tokens of the practices themselves do some of the work in structuring the social categories into which the practices fall. Giddens (1984) gives an account of what he calls “structuration”, the process by which social structures are dynamically generated by practices and also condition them. Sahlins (1981, 1985) describes the formation of cultural categories through collisions between cultures and the actions of individuals. Other theories as well, such as Foucault (1976, 1977a) and Geertz (1973) can also be understood as giving accounts of how practices set up social categories.