General Overview

 Schubert's piano miniatures for two hands were, with the exception of dances and variations, primarily composed in his later years. The Four Impromptus, D 935 (Op. 142), are no exception, and thus are counted among his representative piano works, exhibiting Schubert's mature stylistic characteristics throughout.

 The exact period when Schubert began composing this collection is unclear, as the autograph manuscript of the first piece bears no date. Research based on the watermarks of the autograph manuscripts estimates the composition period to be summer 1827, and since the final manuscript of this collection contains a note dated December 1827, it is believed to have been composed in the latter half of 1827, similar to D 899. While the autograph manuscript of D 899 bears the title “Impromptu” written not by the composer but by the publisher Tobias Haslinger, the title for this collection (D 935) was inscribed by Schubert himself.

 Originally, Schubert had numbered the four pieces of D 935 as Nos. 5-8, intending them for publication alongside the four pieces of D 899 under Haslinger. However, realizing the difficulty, the composer approached Schott & Co. in Mainz in February 1828 regarding the publication of the four pieces of D 935. Schott & Co., after consulting with their Paris branch, concluded that these works were “too difficult for miniatures” and thus could not be published in either Germany or France. Consequently, the collection was eventually published by Diabelli & Co. in Vienna in April 1839. This was more than ten years after Schubert's death.

 Robert Schumann intuitively grasped the nature of this collection. When he brought the four pieces of this collection to public attention in the Neue Zeitschrift für Musik (December 1838) before their publication, he found it hard to believe that Schubert had named them “Impromptus,” and instead suggested that the four pieces formed a “Sonata.” Schumann, who had shown an early understanding of Schubert's instrumental works—having discovered Schubert's Great C Major Symphony, D 944, and led its premiere, and having championed his piano sonatas through his critiques—certainly hit upon the essence of the matter. This is evident when considering the difficulties in publishing this collection, given that it was not as easy to perform as “miniatures” were expected to be at the time, and its scale was also considerable.

 On the other hand, Schumann's observation is not entirely sufficient. This is because it is plausible that Schubert, while aware that this collection was comparable to a sonata, deliberately chose not to name it “Sonata.” For instance, while Beethoven conducted various formal experiments within the sonata genre, Schubert adhered to traditional forms in works he explicitly titled “Sonata.” Therefore, it is conceivable that Schubert, while keeping the sonata in mind, gave these pieces a different title to convey that they were not confined by the sonata's framework. The fact that all eight pieces were initially given continuous numbering suggests that the composer did not necessarily conceive of a four-movement structure. Furthermore, the use of freely interpreted sonata form in the first piece of both collections, and the tonal relationships between the pieces extending beyond closely related keys, also indicate that the Impromptus were composed with greater freedom than sonatas (see analysis of Piece No. 1).

 However, this by no means implies that the Impromptus are less complete than sonatas. For a composer who adhered to traditional forms in sonatas, the Impromptus must have been a space where he could compose in a relatively free style. Viewed this way, it becomes understandable that they are fully imbued with the essence of Schubert's later years.

Analysis of Each Piece

Piece No. 1: Allegro moderato, F minor, 4/4 time

 This piece, positioned at the beginning of the collection, possesses a structure that consciously employs sonata form while also making efforts to avoid stark contrasts.

 The piece opens with the majestic presentation of the first theme in F minor. After the first section closes with a perfect cadence, a second section emerges softly in F minor, featuring mist-like sixteenth notes. At measure 21, it modulates to A-flat major, and as the climax subsides, the second theme is presented in A-flat major from measure 45. Indeed, the quiet presentation of a new theme in the relative major seems to create a contrast with the first theme. However, the modulation to the relative major occurs even before the second theme is presented, and the second theme itself is built upon the skeletal structure of the previously introduced sixteenth-note motive. In other words, while the first and second themes are schematically constructed to be contrasting, in reality, they transition smoothly into each other. This fact can be understood as a result of Schubert's unique adaptation of sonata form, similar to the first piece of Impromptu D 899. This is precisely why it was noted in the general overview that Schumann's assertion, while essentially accurate, was not entirely sufficient.

 From measure 69, a new theme is presented as the middle section. This section begins in A-flat minor, and through the mediation of an E major triad, modulates to A-flat major. The E major, with its sharp key signature, brings a fresh sound, revealing Schubert's characteristic exquisite harmonic transitions.

 At measure 115, the opening theme returns in the tonic key, forming the recapitulation. The second theme, as is typical in sonata form, appears in F major. Furthermore, from measure 182, the middle section is also recapitulated in F minor, and at measure 226, the opening motive briefly returns as a coda, bringing the piece to a close.

Piece No. 2: Allegretto, A-flat major, 3/4 time

 Taking a dance-like 3/4 time, it consists of a main section – trio section – main section da capo, similar to a minuet movement.

 The main section in A-flat major is in ternary form, contrasted by dynamics: soft outer sections and a loud middle section.

 In the trio section, where motion is created by triplets, not only is the basic dance rhythm characteristic of the main section carried over, but the second beat is also further emphasized. The trio section itself is also in ternary form, with soft outer sections in D-flat major contrasting with a loud middle section in D-flat minor. Since the main section is typically given more weight than the trio section, the conception of giving the trio section a scale equivalent to the main section and placing a climax in A major is innovative.

Piece No. 3: Andante, B-flat major, 2/2 time

 This piece is a set of variations consisting of a theme and five variations, inheriting the virtuosic characteristics of the Viennese Classical period while also incorporating lyrical Romantic elements.

 The theme is based on his own incidental music to the play Rosamunde, Princess of Cyprus, D 797 (also famous as the theme of the second movement of String Quartet No. 13, D 804). In the first variation, the theme takes on a dotted rhythm, and in the second variation, the accompaniment figure becomes lighter, emphasizing the syncopated rhythm. After a solemn B-flat minor is inserted in the third variation, the fourth variation modulates to G-sharp major, where a yodel-like melody resounds. In the fifth variation, it returns to B-flat major, and virtuosic scale passages unfold. Finally, the theme slowly returns, bringing the piece to a close.

Piece No. 4: Allegro scherzando, F minor, 3/8 time

 It takes an extended ternary form. The “scherzando” indicated in the tempo marking is expressed through a Hungarian-style hemiola, treating two measures of 3/8 time as one measure of 3/4 time.

 Enclosed within the light F minor main section of the ternary form is, first, an A-flat major musical idea with smooth scales from measure 87. This is followed by a dance-like idea in A-flat minor from measure 131, and these ideas appear alternately twice each. In between, Schubert's trademark enharmonic reinterpretation is used, modulating to A major (with sharps in the key signature) and C major. At measure 336, the main section returns, and from measure 420, a coda develops using the characteristic hemiola rhythm of this piece, bringing it to a climactic close.

 In this analysis, considering the dance-like “scherzando” character, the piece has been broadly treated as a ternary form. However, given that the main section itself is also in ternary form, it could also be interpreted as a rondo form due to the repeated appearance of the opening theme.