The museum is one of the classical 19th century bourgeois institutions. This study offers an explanation of the phenomenon in terms of historical changes in society as well as in mentality, aside from interpretation concepts analyzing the idea of museum, which still dominate. On the basis of the genesis of the museums in Osnabrück as the micro-historical environment, the study takes a closer look at the general history of both bourgeoisie and museum. In particular, it can be shown that, instead of an one-way influence from centre to periphery, the mutual interaction was and is far more distinct than has been recognized up to now. The analysis focuses on an anthropology of collecting, thereby clarifying the relation between the museum as an institution and the development of bourgeois identity. By showing the musealization and professionalization at that period to be a process of institutionalization of collecting, it becomes visible that the museum functioned as a space of museal socialization ("Museale Vergesellschaftung"), in which social borders could also be overcome. Furthermore, it illustrates that museums must be understood far more as "museum individuals", considering the strong individual shaping of museum collections, which originate in the perpetuation of life biographies.