How Beethoven builds a slow movement from one turn of phrase, a single excursion to a new key, and a left hand that keeps time between the themes.
The movement opens with a low, rolled chord and, high above it, a small turning figure that rises by step. Chord and turn answer each other, and then the pair repeats a fifth higher. That turn is the main theme's principal line, and it does not stay in the right hand: in the answering phrase it passes into the left hand's inner voice and back again, bar by bar, while the harmony darkens beneath it and a deceptive cadence turns aside to the relative minor before the phrase is allowed to close. When the theme ends, the left hand takes over with a low, drumming octave that fills the music between the themes and never sounds inside one.
Beethoven keeps the movement in B♭ major under a single key signature and visits only one other key, the dominant. The transition carries the music there, the second theme sings in a plain, song-like texture, and the visit closes only with imperfect cadences; the key never receives a perfect one. The colour comes from elsewhere. Notes borrowed from the minor mode darken the home key, yet the minor tonic itself never appears, and a diminished seventh, respelled for wherever it is heading, supplies the chromatic turns.
There is no development. After the second theme the drum returns, and one chord is held and then climbed a note at a time, each step opening the span wider, until the top line reaches an accented peak and falls away in a long unaccompanied descent that lands back on the opening. The passage is short, but it does a development's work as a hinge between the key of the dominant and the return, and it is the movement's first wave of real tension.
The recapitulation brings back the main theme in a new dress. The right hand is almost untouched, but the left hand now pours continuous fast notes across the keyboard, so the answering phrase becomes by far the busiest music of the movement. With the transition that follows, it makes the climax, which is a zone (mm. 51–70) rather than a point: the densest writing, the widest spacing and the highest note in the piece all fall within it, and the dynamics never pass forte. The transition that once led to the dominant now stays at home, and the second theme returns in B♭ major, which completes the form. The coda restates the main theme's answering phrase, thinned, with the high turn once again standing alone, and the movement ends on its home note, in the bass, by itself.
| Section | Bars | Tonal area |
|---|---|---|
| Exposition | 1–37 | B♭ major to F major |
| Retransition | 38–42 | F major back to B♭ major |
| Recapitulation | 43–88 | B♭ major |
| Coda | 89–103 | B♭ major |
Bar numbers follow the Breitkopf & Härtel edition (Beethovens Werke, Volume XXI No. 140), counted continuously from the first bar; the movement has no repeats. The retransition is shown separately here.
The movement's key plan is a single round trip. The exposition leaves B♭ major for its dominant, F major, and returns; the recapitulation declines to make that move, so the second theme, first heard in F, comes back at home. That return is what turns a two-theme movement into a sonata form. Everything else that sounds like a change of key is a passing lean with no settled arrival, and the borrowed minor colour never becomes a key of its own. The effect is of a very stable movement that colours its home key from the inside.
Home to the dominant and back. F major is the only new key, and it is reached once.
The visit is withheld. The transition stays at home and the second theme returns in B♭ major, so the expected move to F never happens.
No change of key. The music stays in B♭ major and closes the movement there.
The study guide traces every key change in its Global Tonality section and lists them in Appendix B, the Index of Key Changes.
The main theme settles at home with the movement's most conclusive close. The transition rests on a half cadence, a pause rather than an arrival, and the second theme closes in the new key with softer, imperfect cadences, never a perfect one.
The cadences return in the same order, and the deceptive cadence again turns aside before the main theme is completed. The second theme now closes at home, in the same softer way.
A deceptive cadence turns aside once more, and a perfect cadence then closes the theme. Nothing after it is cadential.
Several of the movement's arrivals can be heard two ways. The arrivals that join the exposition's themes are elided into what follows, the closing section dissolves into the coda without any cadence at all, and the long held chord of the retransition resolves into the return only by convention. Both readings stand, and the study guide records both.
Every cadence is located and classified in the study guide's Appendix A, Confirmed Cadence Locations.
For each it gives the bar, the type, the approach and the key.
Beethoven works in contrasts of texture more than of key. The main theme is a high, singing turn over a low held octave; the music between the themes is a rapid drum in the bass alternating with small chords; the second theme is a plain melody over an accompaniment. The range is wide, from the bottom of the keyboard to a high echo of the drum that is the highest note in the piece, but the dynamics stay modest. The music begins quietly and mostly stays so, never goes beyond forte, and in the last third sforzando accents take the place of the loud marks. Even the climax is made by density and spacing rather than by volume.
Analysis and study materials published as they appear.