Piano four-hands

Piano four hands (French: À quatre mains, German: Zu vier Händen, Vierhändig, Italian: a quattro mani) is a type of piano duet in which the two players play on a single piano. A duet with the players playing separate instruments is generally referred to as a piano duo.

Music written for piano four hands is usually printed so that the part for each player occupies the page which is directly opposite to him. The upper part, for the pianist sitting on the right and with the music on the right side of the page, is called primo, while the lower part, for the pianist on the left, is called secondo.

By far the greater proportion of music "à quatre mains" consists of arrangements of orchestral and vocal compositions and of quartets and other groups for stringed instruments. Indeed, scarcely any composition of importance for any combination of instruments exists which has not been arranged and published in this form, which on account of its comparative facility of performance is calculated to reproduce the characteristic effects of such works more readily and faithfully than arrangements for piano solo. Such arrangements were especially popular before the development of recording technology, as the vast majority of the time there would be no other way to hear many of the best-known works of music.

However, the increase of power and variety obtainable by two performers instead of one offers a legitimate inducement to composers to write original music in this form, and the opportunity has been by no means neglected, although cultivated to a less extent than might have been expected.

The earliest known printed works for the pianoforte à quatre mains were published in Dessau about 1782, under the title Drey Sonaten füre Clavier als Doppelstücke fur zwey Personen mit vier Handen von C. H. Müller. However, before this, Ernst Wilhelm Wolf, the musical director at Weimar in 1761, had written one or more sonatas for two performers, which were published after his death. So far as is known these were the first compositions of their kind, although the idea of the employment of two performers (but not on one instrument) may have originated with Johann Sebastian Bach, who wrote three concertos for two harpsichords, three for three, and one for four, all with accompaniment of stringed instruments. But the short compass of the keyboard, which in Bach's time and indeed until about 1770 never exceeded five octaves, was ill-adapted to the association of two performers on the same instrument, and it is doubtless on this account that the earlier composers have left so little music of the kind.

...
Wikipedia