Medial Caesura, EEC, and a Third-Related Second Theme
A candidate is analyzing the exposition of a Classical sonata-form movement in C minor, 4/4, Allegro. Bars 1–8 present the principal theme as a sentence: a two-bar basic idea (C–D–E-flat ascending motive), a two-bar repetition, and a four-bar continuation ending on a half cadence in C minor at b.8. Bars 9–20 are a transition: a sequence over a G pedal, ending with a half cadence on G at b.20. Bars 21–32 present a subordinate theme in E-flat major, a period whose antecedent ends on a half cadence in E-flat at b.24 and whose consequent ends with a perfect authentic cadence in E-flat at b.32. Bars 33–44 are a closing section with repeated cadences in E-flat. The subordinate theme begins with the principal motive transposed to E-flat and augmented. The candidate must locate the essential expositional closure (EEC), decide whether b.21 is a true second theme, and explain the G pedal at b.20.
1. Where is the EEC? Justify by cadence type and key, and explain why b.24 cannot serve as the EEC.
Read the worked answer
The EEC is at b.32, the perfect authentic cadence in E-flat major. An EEC requires a structural authentic cadence in the secondary key that closes the exposition's tonal trajectory. At b.32 the dominant B-flat resolves to E-flat with the tonic in the soprano, and the following closing section confirms E-flat with repeated cadences.
b.24 cannot be the EEC because it is a half cadence in E-flat, not an authentic cadence. It closes the antecedent of the subordinate theme and creates continuation, not structural closure. Treating b.24 as the EEC would leave the consequent without a formal job and would misread the period structure of bb.21–32.
2. Is the G pedal at b.20 a dominant preparation for E-flat or for C minor? What does its resolution at b.21 imply about the tonal plan?
Read the worked answer
G is the dominant of C minor, not of E-flat; the dominant of E-flat is B-flat. The G pedal therefore prepares a half cadence in the tonic and functions as a medial caesura on V. The arrival of E-flat at b.21 is a third-related shift from C minor to its diatonic mediant, not a dominant-prepared tonic arrival.
This means E-flat is not confirmed as a new tonic until the PAC at b.32. The exposition uses a medial caesura on the tonic dominant, then reinterprets the tonal space by moving to III. That is why b.21 can sound like a new theme without yet being a structurally closed secondary key.
3. How does the augmented statement of the principal motive affect the thematic process? Does it make b.21 a 'second theme'?
Read the worked answer
The augmented motive creates motivic linkage between the principal and subordinate themes, supporting unity across the exposition's tonal contrast. But thematic identity in sonata form is not determined by new melodic material alone. b.21 is a subordinate theme because of its tonal function: it establishes the secondary key, leads to the EEC at b.32, and is confirmed by the closing section. A shared motive can coexist with a new formal function. Calling b.21 'not a second theme' because it reuses the motive would confuse thematic material with formal role.