90 and 142 , are a series of pieces for solo piano composed in 1827 and first published during the composer's lifetime (or shortly thereafter) under that name.
90和142，是在1827年组成的钢琴独奏作品系列，首次在作曲家的一生下该名称（或稍后）出版。 There are eight such Impromptus in total.总共有8个这样的即兴曲。
Three other unnamed piano compositions, written in May 1828, a few months before the composer's death, are alternatively indicated as Impromptus or Klavierstücke .其他三个无名钢琴作品，1828年5月去世的书面作曲家的，几个月前，是交替显示为即兴或Klavierstücke（“钢琴曲”）。
The Impromptu s are often considered companion pieces to the Six Moments musicaux , and they are often recorded and published together. S是的即兴作品往往被认为伴侣的六矩musicaux ，他们往往一起录制并出版。
It has been said that Schubert was deeply influenced in writing these pieces by the Impromptus , Op.有人说，舒伯特的作品深深影响了即兴曲 ，写这些作品的。 7, of Jan Václav Voříšek (1822) and by the music of Voříšek's teacher Václav Tomášek . 7， 1月瓦奇拉夫米沃日谢克 （1822年），由教师音乐沃日谢克的瓦茨拉夫托马斯克 。
Franz Schubert's Impromptus, Opp. 90 and 142 (posth.), are a series of pieces for solo piano composed in 1827 and first published during the composer's lifetime (or shortly thereafter) under that name. There are eight such Impromptus in total.
Three other unnamed piano compositions, written in May 1828, a few months before the composer's death, are alternatively indicated as Impromptus or Klavierstücke ( piano pieces ).
The Impromptus are often considered companion pieces to the Six Moments musicaux, and they are often recorded and published together.
It has been said that Schubert was deeply influenced in writing these pieces by the Impromptus, Op. 7, of Jan Václav Voříšek (1822) and by the music of Voříšek's teacher Václav Tomášek.
Four Impromptus, Op. 90 (D. 899)
The Opus 90 impromptus consist of 4 typical Romantic-era pieces, each with distinct elements.
No. 1 in C minor
The first Impromptu, written in C minor, commences with two widely spaced G octaves, leaving the key of the piece ambiguous. The piece continues into a march-like melody played first without accompaniment. The melody is repeated with a chordal accompamiment. (At the end of this statement the key is revealed: after a rising bass, the C minor chord is played in root position.) The march theme is embellished, then leads slowly into the key of A-flat major, where an apparently new melody is introduced. This melody is actually based on the opening melody: the first three notes are spread out more in their intervals but the following three repeated notes remain. Its songlike quality, accompanied by triplets in the bass, contrasts with the march quality of the opening. An extension of this melody takes the final turn and repeats it several times in different registers. When the main theme returns for the first time, it has combined with the triplet pattern of the previous section. Later a new pattern with straight (non-triplet) semiquavers is used as accompaniment, and then an off-beat version asserts itself in quavers. This eventually leads into the extension of the second theme again, this time in G major, using the end of the theme's tonic chord as an effective dominant chord transition into the main theme. The theme gradually dies away and leads to C major, resolving the piece's tension into tranquility. This is the longest impromptu in this set. The tonal ambiguity at the start of the piece highlights the romantic composer's need for abstract imagery through music.
No. 2 in E-flat major
Set in E-flat major, the piece begins with a lively scale-based and often chromatic melody in triplets; the B section moves to E-flat minor and follows a set of chord changes later borrowed for Fly Me to the Moon . This section is darker that the opening though still very lyrical. The section ends with two oscillating figures which act as an important bridge both here and later. The first section repeats but moves quickly into a codetta which reasserts E-flat minor and the darker feeling of the B section. A quick ascending scale leads to the C section in B minor (which however contrasting, is based rhythmically off of the implied accents in the structure of the A section (123123123123). This section is based on a figure alternating a widely spaced bare octave and an offbeat accented triplet. The alternation of octave and triplet becomes closer towards the end and the oscilating figures played at the end of section B return to lead back into the opening ABA of the work. The Coda is a modified version of the C section, starting in B minor but alternating that key with E-flat minor. The work ends in E-flat minor.
No. 3 in G-flat major
This serenade is a classic example of Schubert's outstanding lyrical facility, as well as his penchant for long melodic lines. There is little interruption in the fluttering harp-like broken triad accompaniment, creating a tense contrast with the spacious and languid melody—an anticipation of Felix Mendelssohn's Songs without Words. Without repeats, the melody develops into a shadowy and frequently modulating middle section before returning to its relaxed flow. Though written in G-flat major, the work was printed by the first publisher in G major. The original version is now generally preferred.
No. 4 in A-flat major
The fourth Impromptu, in A-flat major, actually begins in A-flat minor, though this is written as A-flat major with accidentals. The opening theme consists of cascading arpeggios followed by murmuring chordal responses. These are repeated and developed, going through C-flat major and B minor before finally reaching A-flat major. There is a subordinate theme, accompanied by the arpeggio figure, varied with triplets. In the central section, in C-sharp minor, the arpeggios are replaced by a chordal accompaniment. This section ventures into the major mode towards its conclusion, but reverts to the minor. The opening section is repeated and the work ends in A-flat major. The tempo marking is Allegretto.
Four Impromptus, Op. posth. 142 (D. 935)
As the first and last pieces in this set are in the same key (F minor), and the set bears some resemblance to a 4-movement sonata, these Impromptus have been accused of being a sonata in disguise, notably by Robert Schumann and Alfred Einstein, who claim that Schubert called them Impromptus, and allowed them to be individually published to enhance their sales potential. However, this claim has been refuted by contemporary musicologists such as Charles Fisk, who established important differences between the set of Impromptus and Schubert's acknowledged multi-movement works
No. 1 in F minor
This Impromptu is written in rondo form, A1–B1–A2–B2–A3. The returning A section appears always in the tonic, F minor; the first B section, B1 is in A-flat major, the relative major, whereas B2 is in the tonic. This structure can also be interpreted as a sonata form without a development section, supporting the view of the four Impromptus as movements of a single sonata. The B episodes contain a passage invoking a unique pianistic effect: the left hand presents short melodic fragments in form of antecedent and consequent, steadily alternating between the upper (antecedent, creating a crossing of the hands) and lower (consequent) registers of the instrument; the right hand accompanies with an even flow of semiquaver arpeggios in the middle register; the sustain pedal further enriches the sonority, and the dynamics are mostly pianissimo, as often in Schubert's music.
No. 2 in A-flat major
This Impromptu is written in the standard minuet form. Its main section features a melody with chordal accompaniment. The opening bars of the melody are highly reminiscent of a similar theme from the opening of Beethoven's Piano Sonata in A-flat, Opus 26. Alfred Einstein has mentioned another similar theme by Beethoven – in the third movement of the Piano Trio Op. 70 #2. The middle section of the Impromptu, marked Trio as standard in minuets, is contrasted in character with the main section. It is written in D-flat major, and features continuous triplet motion. The second part of the Trio moves to D-flat minor (written in the same key signature but with accidentals added), then climaxes on A major (written without a key signature), fortissimo, and finally calms down and repeats the major-mode first phrase.
No. 3 in B-flat major
This Impromptu in B-flat major is a theme with variations. The main theme resembles a theme from the incidental music that Schubert composed for the play Rosamunde, which also appears in the second movement of his 13th string quartet. The variations follow the classic pattern utilized especially by Beethoven – elements include increasing subdivision and ornamentation, and a departure from the home key in the central variations, before returning to the tonic in the final full variation and the partially-complete coda – see the Arietta of Beethoven's Op. 111.
No. 4 in F minor
This Impromptu contains interesting hemiola effects, brilliant passagework as well as cross modulations that take this piece to keys not traditionally associated with F minor. It is written roughly in Rondo form and contains a coda that further heightens the drama in this already intense piece. The work is the most technically demanding of the Impromptus, employing a wide variety of keyboard writing, including scale runs (at times in unison), arpeggios, broken chords, quick passages in thirds, and trills. Extreme harmonic and rhythmic effects, combined with demonically charming melodies, make this a dazzling and fascinating display of keyboard facility. The piece can be played appropriately at extreme tempos.