Bach's themes and melodies. In transcription of this form, the new piece can simultaneously imitate the original sounds while recomposing them with all the technical skills of an expert composer in such a way that it seems that the piece was originally written for the new medium. But some transcriptions and arrangements have been done for purely pragmatic or contextual reasons. For example, in Mozart's time, the overtures and songs from his popular operas were transcribed for small wind ensemble simply because such ensembles were common ways of providing popular entertainment in public places. Mozart himself did this in his opera Don Giovanni, transcribing for small wind ensemble several arias from other operas, including one from his own opera The Marriage of Figaro. A more contemporary example is Stravinsky´s transcription for four hands piano of The Rite of Spring, to be used on the ballet's rehearsals. Today musicians who play in cafes or restaurants will sometimes play transcriptions or arrangements of pieces written for a larger group of instruments. Other examples of this type of transcription include Bach's arrangement of Vivaldi's four-violin concerti for four keyboard instruments and orchestra; Mozart's arrangement of some Bach fugues from The Well-Tempered Clavier for string trio; Beethoven's arrangement of his Große Fuge, originally written for string quartet, for piano duet, and his arrangement of his Violin Concerto as a piano concerto; Franz Liszt's piano arrangements of the works of many composers, including the symphonies of Beethoven; Tchaikovsky's arrangement of four Mozart piano pieces into an orchestral suite called "Mozartiana"; Mahler's re-orchestration of Schumann symphonies; and Schoenberg's arrangement for orchestra of Brahms's piano quintet and Bach's "St. Anne" Prelude and Fugue for organ. Since the piano became a popular instrument, a large literature has sprung up of transcriptions and arrangements for piano of works for orchestra or chamber music ensemble. These are sometimes called "piano reductions", because the multiplicity of orchestral parts—in an orchestral piece there may be as many as two dozen separate instrumental parts being played simultaneously—has to be reduced to what a single pianist (or occasionally two pianists, on one or two pianos, such as the different arrangements for George Gershwin's Rhapsody in Blue) can manage to play. Piano reductions are frequently made of orchestral accompaniments to choral works, for the purposes of rehearsal or of performance with keyboard alone. Many orchestral pieces have been transcribed for concert band. Transcription aids Notation