Despite the attention that the affective sphere has reached in the last decades, affectivity has generally been supposed to be a consequence of historical processes, not changing their direction. This article argues instead that affectivity can be a driving force in historical change, and it establishes the concept of ‘patheme’ in relation to Michel Foucault’s ‘episteme’, Martin Heidegger’s ‘history of being’ and the notion of regime in William Reddy, Jacques Rancière and Peter de Bolla. What is described as a pathemic change took place in the thoroughgoing affective transformation of European culture during the 18th century, a cultural change that in Sweden was condensed into much more compressed shifts during the Gustav III’s reign (1772–92). This latter period is bestowed an investigation grounded in an understanding of historical processes that considers the interplay between layers such as power relations, social conditions and modes of scientific thought along with affectivity. The interplay is described in terms of polyphony.