Of all the piano concertos that Mozart wrote, only two of them are in a minor key. The first of these is Mozart’s 20th piano concerto in D minor. Although all of Mozart’s piano concertos get played frequently, this one is often a favorite of pianists because of the high level of drama that Mozart creates with his orchestration. From the very beginning of the first movement, the strings take up a restless melody that, although quiet, is insistent and anxious. Punctuated by the horns as the energy builds, the orchestra soon heralds the arrival of the pianist.
All of the piano parts in Mozart’s concertos are filled with immensely complex scales and arpeggios that, while lovely for the listener, are very technically difficult for the pianist. Listening to such passages brings to mind the complaint that Emperor Joseph II of the Holy Roman Empire made to Mozart about his opera Die Entführung aus dem Serail: “that is too fine for my ears—there are too many notes.” However, when listening to the simplicity of the pianist’s opening statement, I am inclined to agree with Mozart’s response: “there are just as many notes as there should be.” However, once the orchestra returns, Mozart is quick to show us some of those pianistic fireworks that he was so adept at.
One of the things that makes Mozart’s concertos so effective is the way that Mozart puts the piano in conversation with the orchestra. I always enjoy listening to the passages in the piano when the melody has been given to the orchestra because these are the moments when Mozart really demands a lot from the pianist. In many of these moments the piano is not going to be the part that you walk away humming, because the figurations dance around the melody without ever actually touching it.
There is a very noticeable moment at the end of the first movement that merits comment. In any recording or performance of Mozart’s piano concertos that you hear today, you will very likely be hearing music that was composed by someone other than Mozart. At the end of the first movement in all of Mozart’s concertos is a moment when the orchestra plays a very dramatic unresolved chord sequence called a half-cadence, and then stops and waits while the pianist plays a cadenza. In a cadenza, the pianist will perform music based on the melodies of the concerto. In Mozart’s time the pianist would have improvised this music in front of the audience – bear in mind that Mozart wrote his piano concertos for his own personal use, so this would not have been as challenging for him than it would have been for someone who had not already composed the entire concerto. Today, pianists have the option of performing an already-composed cadenza. The 20th concerto has a particularly excellent selection of cadenzas to choose from, with cadenzas written by Ludwig von Beethoven, Johannes Brahms, and Clara Schumann readily available. While Mozart wrote and published cadenzas for several of his concertos, I find that for some reason they aren’t usually performed very often. With the completion of the cadenza, the pianist is finished with the first movement and the orchestra very quickly brings the first movement to a close.
Like most second movements in Mozart’s compositions, the second movement of the 20th concerto is somewhat slow and very elegant. Nonetheless, he finds ample opportunity to show off his technical abilities. This movement opens with a very serene melody with a simple accompaniment that moves between the orchestra and the piano. However, Mozart takes the opportunity to write a very complicated piano figuration on top of that serene structure after a while. Up to this point the support for the melody has been very clearly divided into duplets, but he further divides this into triplets for a period. He manages to retain a surprising amount of the sense of placidity from before with the sustained notes in the woodwinds that play under the pianists rolling triplets. The non-stop triplets eventually give way to the return of the serene elegance of the beginning of the movement.
The third movement begins with the piano, rather than the orchestra, as in the first movement. This movement features a lot more call-and-response between the piano and the orchestra than has happened previously. This movement also features a cadenza, but having a cadenza in the third movement of a concerto is not as standard as having one in the first movement.
A note about Mozart’s key choice—a number of Mozart’s more famous works were written in the key of D minor. In addition to this concerto, much of the opera Don Giovanni is written in D minor, particularly the portions in which the title character is quite literally dragged to hell, as well as the aria “Der hölle rache koch in meinem herzen” from Die Zauberflöte. Mozart’s very last composition, the Requiem that he left unfinished at his death was also in this key.
When listening to this concerto, try to feel the drama that Mozart conveys, and try to hear the darkness that Mozart associated with the key of D minor. This is one of his later concertos, so he’s got a very well-developed sense of musicianship, which shows in his balance between the piano and the orchestra.