Completed two months before his death, today’s choice was composed for the clarinettist Anton Stadler – the Clarinet Concerto by Mozart.
This is a very short version of the story: Stadler had taken the chalumeau (a sort of recorder with a clarinet mouth piece) – Vivaldi had written concerti for it – and extended it considerably, creating what we know as the basset horn, or the basset clarinet (not the bass clarinet).
Mozart then used this instrument in his orchestra, notably in his Requiem, this concerto, a quintet for clarinet with strings, and also in his final symphonies.
The wonderful Antony Pay demonstrates this here: https://www.youtube.com/watch?v=D3NCGSvKHCQ
Listening Project 