One of the broad trends in sonata formal practice from the later half of the 19th century is the expansion of thematic areas through nesting multi-sectional forms within them. For example, the primary theme area frequently consists of a nested ternary form, complete with its own formal functions. The B section in a ternary form usually contains transitional rhetoric, and thus some degree of transition function. The B section does not function as a transition for the sonata movement, however, since the stable A section of the nested form reprises before the movement’s transition segment commences. Such a nested ternary form highlights different functional levels at work during the primary theme area: a surface level that encompasses the functions of the ternary form, and a deeper-level primary theme function that works on the level of the entire movement. Hierarchical functional levels also result when a double second group combines with a trimodular block, creating a nested two-part sonata exposition within the secondary area; double second groups that do not utilize a trimodular block structure can resemble a nested continuous exposition.
The presence of nested forms and the hierarchical formal levels they create impact the processes of the entire sonata. For example, the abbreviation of formerly nested ternary forms within the primary theme represents an integration of the hitherto independent form into the drama of the sonata movement as a whole. At the same time, the hierarchical formal levels collapse, since the surface-level functions disappear. Drawing on the work of Warren Darcy, James Hepokoski, Steven Vande Moortele, Janet Schmalfeldt, and James Webster, this paper explores the implications of nested forms and hierarchic formal levels in sonata forms by Brahms, Dvořák, and Grieg.