Schubert - Impromptu Op. 90, No. 1 in C minor, D. 899 [HD]

Franz Schubert's Impromptus are a series of eight pieces for solo piano composed in 1827. They were published in two sets of four impromptus each: the first was published in the composer's lifetime as Op. 90, and the second was published posthumously as Op. posth. 142. They are now catalogued as D. 899 and D. 935 respectively. They are considered to be among the most important examples of this popular early 19th-century genre.
Three other unnamed piano compositions (D. 946), written in May 1828, a few months before the composer's death, are known as both Impromptus and 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 (1822) of Jan Václav Voříšek and by the music of Voříšek's teacher Václav Tomášek.

The first Impromptu, written in C minor, is a set of variations on two themes. It 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 accompaniment. (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.