General Overview

After concentrating on string quartets from 1810 to 1813 and symphonies from 1813 to 1816, Schubert dedicated 1817 to the composition of piano sonatas. The fact that he composed his first piano sonata in 1815 and then engaged in further trial and error in 1817 indicates that Schubert began working on piano sonatas relatively late compared to other genres. In any case, this work marks the beginning of the 'Year of Piano Sonatas' in 1817.

Although this work is known as 'Piano Sonata No. 4,' the composer himself inscribed '5te Sonate' (5th Sonata) on the autograph manuscript, and the reason for this numbering discrepancy is unclear. Possible explanations include:

• The possibility that D 154, now considered an alternative version or compositional process of Sonata No. 1 (D 157), was counted as one sonata.
• The possibility that another sonata was written but has since been lost.
• The possibility that D 279, which the composer himself marked as 'No. 1,' was counted as the first, and the three violin sonatas composed in 1816 (D 384, 385, 408) were counted as Nos. 2-4.

This work is considered a complete three-movement sonata, given its tonal structure, beginning and ending in A minor, and the inscription 'Fine' at the end of the third movement in the autograph manuscript.

Movement-by-Movement Analysis

Movement 1: Allegro ma non troppo, A minor, 6/8 time

It is in sonata form. The movement opens forte with the tonic chord of A minor, then crescendos from p towards a dominant ninth chord. This three-measure antecedent phrase is followed by a two-measure consequent phrase consisting of an arpeggiated dominant ninth chord, after which the theme is presented again. The unstable character of the theme is emphasized not only by the dynamic range but also by the irregular phrase structure of 3 measures + 2 measures. After the re-presentation of the theme, the music does not remain in A minor but modulates several times to remote keys already within the exposition.

After being separated by a general pause, the second theme is presented in F major (m. 28). Choosing a major key a major third below the tonic, rather than the relative major, was by no means a violation of rules for Schubert (cf. Unfinished Symphony, D 759). Both themes contrast in terms of dynamics and character.

At the end of the exposition, modulations are layered through the repetition of motives, thereby introducing the development section (m. 73). The development section is also divided into two parts by a general pause, characterized by the contrast between a forceful first half, beginning in sharp keys and played loudly, and a lyrical second half, beginning in flat keys and played softly.

When the development section closes with a half cadence in D minor, the first theme returns in D minor after a general pause. Recapitulation in the subdominant key is famous in the first movement of Mozart's Piano Sonata in C major, K. 545, first movement, but Schubert had already used this technique in Piano Sonata No. 2, D 279, and No. 3, D 459. Utilizing the tonal relationship of the exposition, which progressed to a key a fifth above, the second theme returns in A major, and the opening motive appears as a coda, bringing the movement to a close.

Movement 2: Allegretto quasi Andantino, E major, 2/4 time

It takes the form of a rondo, where a 16-measure refrain repeatedly returns, interspersed with two types of couplets. In the tranquil opening theme of the movement, presented in E major, the right hand plays legato while the left hand plays staccato. From measure 17, the first flowing couplet, featuring sixteenth notes, appears in C major. The refrain returning at measure 43 is in F major, and its accompaniment rhythm carries over the sixteenth notes from the preceding couplet. From measure 59, the second couplet appears, taking a march-like eighth-note accompaniment in D minor. From measure 115, the refrain returns in the tonic key. Here, it takes yet another accompaniment figure and concludes with a 14-measure closing section.

Notably, the melody of this movement's refrain would later be used again as the theme for the fourth movement of Piano Sonata D 959.

Movement 3: Allegro vivace, A minor, 3/8 time

It takes a cyclical form of A-B-C-A’-B’-C’-A’’-Coda, with each section separated by a general pause. First, the opening theme (A) is presented in A minor through a scalar unison. This theme is always played fragmentarily, suspended by a half cadence. Following this, a new, active theme (B) appears in A major (m. 31), and from measure 59, a new theme (C) is presented dolce. This theme C begins in D major, but after an intervening section in E major, theme C reappears, remaining in E major. From measure 164, the previously presented material is recapitulated in different keys. The opening theme is in E minor, theme B is in E major, and theme C begins in G major before modulating to A major. Following this, the opening theme returns in a shortened form in the tonic A minor (m. 310), after which a coda full of dynamic contrasts appears, concluding the piece in A major.