At the beginning of the 19th century, a fundamental change in the Western worldview began: the dynastic worldview prevailing since the 16th century, explaining social order, chronology and geography with reference to genealogy, was challenged by new nationalist ideas (BenedictAnderson, Imagined Communities). This process lasted most of the century, and was characterized by a struggle for interpretive precedence. How should the ideas that constitute theworldview be understood? What weight should they have? Here, different social strata stood against each other, since the nationalist worldview include ideas of equality, democracy and, by extension, a shift of power. One way to address this was precisely by reinterpreting the meaning of the novel ideas and making them compatible with the prevailing social order. Particularly important for this interpretive work was the cultural life, where the worldview was primarily shaped. Here music played an important role, particularly since its significance for wider social groups increased markedly during the period. Part of a larger project ranging throughout the 19th century, this paper focuses on the Swedish Royal Opera in the first half of the century. Taking leads from James H. Johnson (Listening in Paris, 1995) and Michael Walter (“Die Oper ist ein Irrenhaus”, 1997) I show how this institution and its associated affective practices contributed to the interpretations of the nationalist ideas. Fundamentally propagandistic, the institution itself contributes to the understanding. The occurrence and use of nationalist ideas in this arena fit their meaning to the dynastic worldview. Music is studied as an affective practice, acknowledging how the practice gives music affective value. To a large extent, it is in practice that music conveys the new ideas. The practice determines the meaning, to a greater degree even than the music itself.