Sonata Theory - Key Concepts

Key Concepts

Sonata Theory understands the rhetorical layout of a sonata as progressing through a set of action spaces and moments of "structural punctuation." These action spaces largely correlate with the "themes" or "groups" of the sonata, though each space is differentiated primarily by the unique generic goal that the music pursues within that particular space. The exposition lays out each space, establishing a rotational order which the recapitulation also follows. Frequently the development will only articulate a subset of these action spaces, moving only through a partial rotation, although fully rotational, entirely episodic, and non-rotational developments also occur.

The primary theme (P) zone or space presents the initial musical material of the sonata, excluding an optional introduction which is not considered part of the sonata form proper. One function of this space is to define the main (or tonic) key of the piece, usually confirming it with a cadence at the end of the theme. Generically, however, the sonata is required to depart from this home key for the later action spaces, so the tonic proposed by P is only provisional; one of the main generic goals of the following sonata form is to eventually affirm this key with a more definitive cadence. A second function of P material is to signal the initiation of one of the sonata's rotations. As P falls at the beginning of the rotational layout and usually consists of distinctive musical material, every subsequent occurrence of that material suggests the beginning of a new rotation.

The transition (TR) follows P, sometimes emerging seamlessly out of it. The chief goal of TR is to build up energy, although TR also frequently modulates away from the tonic to prepare the sonata's secondary key. The most common goal for the transition's energy gain is to drive to the first moment of "structural punctuation," the medial caesura. If this option is chosen, a Two-Part Exposition is produced; if not, TR leads directly to the essential expositional closure (described below), producing a Continuous Exposition.

The medial caesura (MC or ’), if present, is an abrupt gap in the musical texture, either a complete gap in sound or covered over by light "filler" material. The MC is often triggered by repeated, declamatory ("hammer blow") chords and follows either a half cadence or authentic cadence in the tonic or secondary key. (The first level default is to build an MC around a half cadence in the new key; by far the least common option is to set the MC up by an authentic cadence in the tonic.) This moment of punctuation serves one purpose: to announce the impending arrival of the sonata's secondary theme. According to Sonata Theory, a piece cannot have a secondary theme without an MC to prepare it (except in highly deformational circumstances): the medial caesura is a necessary generic marker of the second theme. This is the meaning of the term "Two-Part Exposition:" sonata expositions including a medial caesura are articulated into primary and secondary themes. Those without proceed "continuously" from beginning to closure.

If prepared by a medial caesura, the secondary theme (S) begins in the exposition's new key (normatively V for major mode sonatas and III or v for minor mode ones). Often, and with increasing frequency in the nineteenth century, (but by no means exclusively) the secondary theme is marked by a quieter, more lyrical character than the energetic TR that preceded it. The main objective of the S action space, however, is to confirm the new key with a perfect authentic cadence. This cadence is the overaching goal of a sonata exposition, and its equivalent moment in the recapitulation is the chief goal of the sonata form as a whole. Thus S space is often characterized by dramatic methods of delaying this cadential arrival. (One common manner in which this is accomplished is the articulation of an apparent second medial caesura, producing what Sonata Theory terms a Trimodular Block.)

The authentic cadence that S-space strives for is the essential expositional closure (EEC), the second main moment of structural punctuation in an exposition. (The equivalent moment in a recapitulation is the essential structural closure (ESC).) Usually, the EEC is provided by the first perfect authentic cadence articulated after S-space has begun, although this can be undermined in various ways (such as repeating previously heard material from S, implying that the previous cadence was somehow insufficient and S-space needs to "try again"). Thus the EEC is conventionally defined as "the first satisfactory perfect authentic cadence that proceeds onward to differing material." The EEC confirms the new key proposed by S; it is the generic goal of the exposition as a whole. Likewise, the ESC in the recapitulation confirms the key of S in the recapitulation, which is now the tonic. Thus the ESC confirms the piece's tonic as a whole, solidifying the tonal promise first made by P in the exposition. The entire sonata form, therefore, is understood as a dynamic trajectory toward the ESC, the basic plan of which is foreshadowed by the exposition's approach to the EEC. This teleology is central to Sonata Theory's conception of the dramatic and expressive potential of sonata form as a whole.

Following the EEC or ESC, a composer can append a closing (C) zone that reinforces the key of the cadence. Often this involves further authentic cadences after the EEC, even ones that are more rhetorically forceful, but they serve only to reinforce the closure attained by the EEC. By the definition of the "essential closure" cadences, C must involve musical material that differs from what was heard in S. In fact, C space often includes distinctly new thematic material.

The entire layout of a Two-Part Exposition is thus often represented as:

P TR ’ S ↓ C

(Arrows are frequently used in Sonata Theory notation to represent authentic cadences—in this case the EEC.)