In recent years, one of the more engaging exchanges surrounding sonata form design has been between James Hepokoski/Warren Darcy (2006) and William Caplin (1996) and their respective assessments of secondary and subordinate themes. For instance, Hepokoski and Darcy suggest that despite the possibility of multiple themes following a medial caesura, only the first is important enough to designate its confirming perfect authentic cadence (PAC) as structural—in the exposition, it is labelled the “essential expositional closure” (EEC). They argue that any additional themes are part of a closing zone; put another way, themes within a closing zone are post-cadential—i.e., post EEC.
In contrast to Hepokoski/Darcy, Caplin dispenses with a closing theme designation: he argues that their various descriptions and summaries in the literature are not theoretically consistent and instead considers them as additional subordinate themes. Further, he intriguingly suggests that multiple subordinate themes will undoubtedly have different degrees and types of looseness. Although Caplin does not develop this idea in his treatise, the implication is that a series of subordinate themes can be placed on a continuum based upon the degree of looseness of thematic design. Using this premise as a point of departure, in this paper I examine the subordinate theme groups in the first movement expositions from a number of chamber works by Mozart and generate a narrative for each work, not predicated on extra-musical associations, but rather upon the degree and type of looseness associated with each theme, thereby speculating a rationale for their position within each group. I end with further areas of inquiry with respect to this model of subordinate theme group narrative.