The String Quartet No. 12 in E♭ major, op. 127, by Ludwig van Beethoven, was completed in 1825. It is the first of Beethoven's late quartets. There are four movements:
Maestoso — Allegro
Adagio, ma non troppo e molto cantabile
The first movement is interrupted several times — just before the development of the sonata form begins, and when that section is almost but not quite over — by the Maestoso which opened the work.
The immense second movement is in the subdominant key of A♭ major. It consists of a set of six variations and a coda. The first variation is in 12/8 meter with darker harmonies and quick changes in dynamics. The second variation increases the tempo to andante con moto but shortens the meter to 4/4. Here, the two violins engage in a dialogue over staccato accompaniment. The third variation shifts to the remote submediant key of E major and the tempo shifts to a hymn-like adagio molto espressivo. The fourth variation returns to 12/8 meter and drops a half-step to the dominant key of E♭ major. This variation has a codetta which transitions the key to D♭ major in preparation for the next variation. The fifth variation is sotto voce and has been called a "mysterious episode" and begins in D♭ major and transitions to C♯ minor (the enharmonic equivalent to D♭ minor). The recapitulatory sixth variation returns to 12/8 meter, presents only half of the theme and connects directly to the coda.
The penultimate variation recapitulates the theme after a contrasting section in the submediant, while the final variation restores the tonic and basic thematic material after an episode in the subdominant. Beethoven based this tonal progression on the finale of the Ninth Symphony (Op. 125) where the orchestral double fugue episode in B♭ is followed by the "grand" variation for full orchestra and choir in D major, followed by the "Seid umschlungen" episode in G major, which moves into the choral double fugue in the tonic D major.
Op. 127: A♭ -> E (lowered submediant) - penultimate variation -> D♭ (subdominant) -> final variation
Op. 125: D -> B♭ (lowered submediant) - penultimate variation -> G (subdominant) -> final variation
The scherzo's trio is a Presto of a kind Beethoven did not use very often, though it is similar in sound and phrasing to some of his bagatelles from the contemporary Op. 126 set.
Beethoven initially planned two additional movements: one between the first and second, and another between the third and fourth.
^ Steinberg, Michael (1994). Robert Winter, Robert Martin. ed. The Beethoven Quartet Companion. University of California Press. pp. 216–227. ISBN 0-520-08211-7.