Having an orchestra around is pleasant enough, but hiring one is rarely the most convenient thing to do. The logistical issues around getting 40 or 50 or 100 or more people to the same place to do the same thing at the same time are steep enough; fitting them into your living room adds a whole new dimension to the problem. So there is a long tradition of reducing large orchestral works to fit a small ensemble — a tradition which was very important for the transmission of music before the age of reduction through recording. It was how music got into the house.
This reduction of Wolfgang Amadeus Mozart’s Piano Concerto No. 20 in D minor, K. 466 by Carl Czerny (a student of Beethoven) has a paradoxical quality. Any concerto, with its virtuosic largeness, is suited best to a public forum and dramatic presentation, and this particular concerto has an unusually large dynamic and emotional scope — it is an entire mature drama, with a cold wind blowing through it. And Mozart, writing for himself at the piano, found in this particular concerto ways to foreshadow (in the first movement) the ambiguous dark forces in Don Giovanni; to extend (as in the second movement) moods from simple Romance to something terrifying in the middle; and to remove almost all celebration (as in the last movement) from the usual rondo finale. The D minor is an enormous piece, not only in itself, but in its expansion and exploration of what musical forces a concerto could contain. By Czerny’s hand it is drastically reduced. But the essential largeness of it remains, and the concerto can still show itself fiercely, even if sometimes only in relief. Though the woodwind section is gone, the sound of the wind remains in the sound of the flute; the harmony retains its strength in the forces of the orchestra-quintet; and none of the piano part — not a note — is in any way altered.