General Overview

 Schubert's piano miniatures for two hands, with the exception of dances and variations, were primarily composed in his later years. The Four Impromptus, D 899 (Op. 90), are no exception, and thus are counted among his representative piano works, exhibiting Schubert's mature stylistic characteristics throughout.

 However, the precise period of composition is not clear, as the autograph manuscript of this collection does not bear a date of composition. According to an investigation of the watermarks on the music paper used for composition, the autograph manuscript is presumed to have been created in the summer of 1827. Given that the publication of this collection was announced on December 10, 1827, it is thought that the detailed refinement followed relatively soon after the initial drafts. The latter half of 1827, when this collection was completed, was approximately one year before the composer's untimely death.

 The originator of the title "Impromptu" is also not clearly known. This is because the title on the autograph manuscript of the first piece was inscribed not by Schubert, but by Tobias Haslinger, who undertook its publication. Furthermore, considering that piano collections of the time were often given titles appealing to the middle class, it is plausible to surmise that the publisher suggested a marketable title. However, circumstantial evidence does not rule out the possibility that Schubert himself named it. This is because Jan Václav Voříšek's Collection of Impromptus (Op. 7) was published in Vienna in 1822, and it is possible that Schubert met Voříšek at an amateur concert at Kiesewetter's house. In any case, since the composer himself inscribed "Impromptu" on the autograph manuscript of the subsequent Four Impromptus, D 935, it is certain that Schubert was satisfied with this title.

 However, it seems that what the composer intended for these "Impromptus" did not align with what the audience and publisher expected. While the publisher expected a collection of small, relatively easy-to-play bagatelle-like pieces, typical of piano collections at the time, what Schubert created was a large-scale collection comparable to a "sonata." Schubert initially hoped that all eight pieces would be published together by Haslinger, and thus numbered the subsequent four pieces as Nos. 5-8. However, after publishing the first two pieces in December 1827, Haslinger became reluctant to publish the remaining six. The latter four pieces were offered by the composer to another publisher, sensing Haslinger's reluctance, while the remaining two from the first set had to wait 30 years to be published.

 It was none other than Robert Schumann who first likened the Impromptu collection to a sonata. In the Neue Zeitschrift für Musik (1838), Schumann reviewed the four pieces of Op. 142 as a "sonata" (for more details, refer to the commentary on Impromptu D 935). Schumann's observation, coming from a keen interpreter of Schubert's works, seems to apply to D 899 as well, as symbolized by the publisher's reluctance to publish. Strictly speaking, however, it is thought that Schubert's most important conception, while keeping the sonata in mind, was actually to differentiate it from a sonata. A work closer to a "sonata" than a "miniature," but one that allowed him to fully express his style without being confined to the sonata form—this was likely Schubert's idea regarding the "Impromptu." Within the framework of a four-movement sonata, as likened by Schumann, the first movement, which typically takes sonata form, is considered formally the most stable. Therefore, by analyzing the first piece, which corresponds to the first movement, in detail, we will specifically examine this point.

Commentary on Each Piece

No. 1: Allegro molto moderato, C minor, 4/4 time

 This piece, positioned at the beginning of the Impromptu collection, corresponds to the first movement in sonata form, if one were to liken the four pieces of the collection to a "sonata." Therefore, this piece is key to understanding its relationship with the sonata, as mentioned in the general overview. We will clarify Schubert's compositional conception through a detailed formal analysis.

 This piece opens with a forceful striking of G notes, layered in octaves. Following this, a monophonic "question" and a harmonized "answer" are played four times, each as a four-bar unit. In doing so, the eight-bar phrase is colored with different harmonies each time, as if illuminating a single object from various angles. This section, which began in C minor, ultimately cadences in A-flat major, and a new section opens in A-flat major (mm. 42ff.). What is noteworthy here is that while the theme of the new section is recognized as the second theme due to its differing key and accompaniment rhythm from the opening theme, it is melodically derived from the opening rhythm of the first theme. In other words, this second theme has an affinity with the opening theme. After the second theme is repeated several times, similar to the first theme, and builds in intensity, a new theme is briefly presented for eight bars in A-flat major from m. 74. This theme is named the third theme due to its new melody, but given the brevity of its presentation and its key, it can also be interpreted as a continuation of the second theme.

 Following this, a five-bar transition derived from the first and second themes leads to a pause, meaning that up to m. 87 corresponds to the exposition in terms of sonata form. Indeed, with multiple themes presented and a modulation from C minor to A-flat major, it can be interpreted as sonata form (although not a relative key, the key relationship of modulating down a major third for the second theme is also seen, for example, in Symphony No. 7, 'Unfinished,' D 759). However, because the first and second themes share the same melodic material, and the second and third themes share the same key, the three themes placed in the "exposition" are designed to have weakened contrast and to transition gradually. In this respect, this piece distinguishes itself from typical sonata form movements where contrast is created between themes. Thus, it highlights Schubert's characteristics, which differ from Beethoven's compositional style marked by the "sublation" (Aufhebung) of two opposing propositions.

 From m. 88, the first half is re-presented, paraphrased in a development-like manner. First, the first theme returns in the tonic key. Here, it is accompanied not only by the triplet accompaniment rhythm derived from the second and third themes, but this rhythm also appears as repeated octaves, creating a sense of urgency. After the eight-bar theme is played twice, it deviates from the theme and builds in intensity. The second theme, originally in a major key, is recapitulated in G minor, adopting a new accompaniment rhythm of sixteenth notes and an off-beat bass line (m. 125). The third theme then returns in G major through an unexpected major-key shift (m. 152). Thus, while this section generally has the character of a development, what is actually played is nothing other than a recapitulation of the first half. It is evident that this piece is constructed more freely than a typical sonata form movement, not only in its structure of merging development and recapitulation but also in its key design for the recapitulation. Avoiding contrasting elements as much as possible in the exposition, incorporating the character of the development into the recapitulation, and performing the recapitulation in free keys—sonata form is interpreted uniquely by Schubert, and despite this piece being comparable to a sonata's first movement, it is clearly differentiated from it. It can be assumed that this is why Schubert did not title it a "sonata."

 From m. 161, a coda based on the first theme begins. Here, the interplay between major and minor keys, a technique Schubert favored in his later years, is employed to its fullest extent. This technique is foreshadowed at the moment the third theme is recapitulated in G major (m. 152) and is used even more vividly in the coda. The coda, which began in C minor, suddenly shifts to C major at m. 167. The key change combined with the sudden shift to pianissimo makes this one of the most prominent passages in the entire piece, similar to the first song of Winterreise. Thereafter, C major is the primary key, but from m. 177, elements of C minor, such as E-flat and F-sharp, emerge, making the future of the major/minor mode uncertain. At m. 192, it seemingly settles in C major, but C minor is glimpsed through E-flat in mm. 194-195 and 199-200, and C major is finally confirmed only in the last four bars.

 The overall tonal structure of the movement, broadly speaking, begins in C minor and ends in C major, thus appearing to align with the "path from darkness to light" (per aspera ad astra) structure popularized by Beethoven. In reality, however, the major and minor modes remain indistinct until just before the close, depicting a story entirely different from a clear-cut major-key apotheosis.

 Reinterpreting sonata form while simultaneously defamiliarizing a linear musical structure through the interplay of major and minor keys—Schubert's distinct direction, established after Beethoven's death, is clearly discernible.

No. 2: Allegro, E-flat major, 3/4 time

 The overall structure is a ternary form: A-B-A-Coda. In the A section in E-flat major, scales in triplets run freely throughout. The A section itself is also in ternary form, with a middle section (mm. 25-51) in the parallel key of E-flat minor inserted. When the opening section is recapitulated in a shortened form, the G-flat major triad (m. 82) is reinterpreted as an enharmonic F-sharp major triad, and with this as the dominant chord, the B section appears in B minor. If written without enharmonic reinterpretation, the B section would originally be in C-flat minor, indicating that the A and B sections are in a mediant key relationship. Both the progression by mediant keys and the technique of moving deeper into the circle of fifths are Schubert's trademarks.

 The dance-like B section contrasts in character with the flowing scales of the A section, yet the basic accompaniment rhythm is common to both A and B sections. In the B section, the removal of triplets from the melody brings the dance-like accompaniment rhythm to the forefront.

 After the A section returns, the B section appears in a transformed state as a coda (mm. 251ff.). The coda begins in C minor and, through successive modulations, closes in E-flat minor, resulting in an unusual tonal structure where the entire piece begins in a major key and ends in its parallel minor.

No. 3: Andante, G-flat major, 4/2 time

 This piece, marked Andante, serves the role of a slow movement in a sonata. However, both the 4/2 time signature and the key of G-flat major (with six flats) were unusual for a "miniature" at the time. Therefore, in the first edition, they were changed to 2/2 time and G major for ease of playability. Here, too, one can see a reason why this collection was so difficult to be accepted.

 Written in ternary form, the melody of the main section in G-flat major is spun from the dactylic (long-short-short) rhythm, which Schubert favored. The middle section modulates to the relative key of E-flat minor. The middle section is given a contrasting character to the main section by its key, its forceful opening, and the urgent triplets in the left hand. However, continuity is maintained by the persistent accompaniment of sextuplets in the middle voice. At the end of the middle section, a trill is placed in the low left hand (m. 53). This is a characteristic Schubertian technique, known from examples such as the Piano Sonata in B-flat major, D 960.

No. 4: Allegretto, A-flat minor, 3/4 time

 It takes a ternary form: Main section—Trio section—Main section, with each section constructed using various chords.

 The main section begins in A-flat minor and is composed of arpeggiated chords in the right hand and a left-hand rhythm emphasizing the second beat. After these four active bars and two quarter-note bars that halt the motion are alternately repeated, an eight-bar sequence of quarter-note chords follows, suddenly modulating to A-flat major. Such sudden shifts between major and minor keys were a favored technique of Schubert. Upon reaching A-flat major, the quarter-note phrases disappear, and the arpeggiated chords, which were in two-bar units at the beginning, contract to one-bar units, creating a sense of urgency. Building on this, a melodic theme first appears in the bass voice (m. 47) and gradually builds to a dissonance (m. 68). As it subsides, the aforementioned theme is played in the upper voice accompanied by triplet arpeggios (m. 72), and sixteenth-note arpeggios return, closing the main section.

 The trio section reinterprets A-flat as G-sharp, becoming C-sharp minor. Here, the melody is supported not by arpeggiated chords, but by repeated chords. The trio section also takes a ternary form, but the main section returns in the parallel major (m. 139), and a major/minor shift occurs.

 When the main section returns, there is no coda; it concludes majestically with a two-chord cadence, remaining in A-flat major. Unlike No. 1, it has an unambiguous major-key ending.