Mozart’s famous and much-played Piano Quartet in E-flat major, K.493, was composed in 1786. A contract with the Viennese publisher F. A. Hoffmeister had commissioned three piano quartets from Mozart, but after receiving the first, K.478 which was deemed too difficult, Mozart was released from the contadct but chose to compose the Quartet in E-flat major K.493 anyway
The quartets owe their existence to chance and Mozart was scarcely aware of the fact that with these works, in what was then still a new form which was to be of great importance in the future, he had established a secure position in chamber music.