Between 1784 and 1786, Mozart composed 12 piano concertos and while the number of compositions itself is impressive, what’s even more impressive is the fact that they don’t all sound the same.
His 24th piano concerto was finished only 3 weeks after his 23rd. Unlike his other piano concertos, No. 24 uses the largest orchestra and includes both oboes and clarinets. It is also one of only 2 Mozart piano concertos written in a minor key.
One of the reasons Mozart was able to finish and perform his 24th concerto so quickly after the completion of the 23rd might have something to do with the fact that he didn’t write out the pianist part completely.
Since Mozart conducted the work from the piano and performed the piano part himself he probably didn’t feel the need to write out the complete part, and there is some speculation that his first performance was partially improvised.
If you are ever in London, England, and have the opportunity to visit the Royal College of Music, you might get a chance to see the original score for Piano Concerto No. 24 in C minor, K. 491. While looking at the handwritten score you can see that the orchestral parts are written out clearly the solo part is incomplete. Sometimes Mozart only wrote the outer parts of passages of scales or broken chords. You can also see some last-minute changes and additions that were made by the composer. There are no tempo markings and there is the occasional notation error in the score, which musicologist Friedrich Blume attributed to Mozart having “obviously written in great haste and under internal strain”.
Apparently, Beethoven and fellow composer/pianist Johann Baptist Cramer attended a performance of this concerto. Beethoven is said to have exclaimed “Cramer! Cramer! We shall never be able to do anything like that!”