Beethovens Quintet for Piano and Winds gestated throughout his teenage years and was his signature chamber piece in his concerts in his teens and early twenties. He didnt put it in concrete and publish it until he was nearly 30.
Mozart had written a quintet for piano and winds, and Beethovens quintet followed Mozarts model exactly. Beethoven even tips his hat to Mozart in the second movement.
While most middle class German-speaking families had members who were string players, not that many families had wind players. To take advantage of the home market, Beethoven arranged the piece for piano, violin, viola and cello. That would permit parents, children and cousins to sit down at home and try out this piece.
Today the problem still exists. Finding string players for chamber music festivals is simple; finding wind players is not. This stems from the fact that chamber pieces with strings greatly outnumber those with winds. Personally I prefer the original wind version of this piece, but finding four wind players to perform it is harder than finding three strings players. This is why this version, the Quartet for Piano and Strings in E-flat, Op. 16, is performed more often.
It starts with a Grave introduction in 4/4 time with the material stated in unison.
At 2:36 the exposition begins in 3/4, marked allegro ma non troppo, which means quick, but dont overdo it.
At 3:48 the second subject arrives in the expected key of B-flat.
At 5:04 the exposition repeats.
At 7:31 Beethoven turns to G minor to open his development section. He wends his way to A-flat for a short statement of the opening theme.
At 9:08 he recaps the first subject in the correct key of E-flat, and the second subject also appears in the correct key of E-flat. So far its a perfectly proportioned classical piece in the mold of Mozart.
But at 11:00 Beethoven puts his own brand on this movement with a coda that begins with a wicked spin. Then he sums it all up and winds it down for a killer ending.