On today’s date in 1789, Mozart was in Dresden, performing his new piano concerto at the Royal Saxon Court. Mozart was pretty good at documenting his own compositions, and we know from a catalog of his works that he finished this concerto in late February the previous year.
Unfortunately for posterity, he was less dutiful in copying out all of the solo piano part, which he no doubt just kept in his head. The surviving manuscript score contains just a shorthand version of the solo piano part, with the music for the left-hand hardly there at all.
Modern performers have to rely on their own wit and imagination to fill in the blanks, and, who knows: maybe he played it differently each time, improvising around his own sketchy outline as the mood took him?
In any case, Mozart must have been proud of this concerto. He played it again at the festivities surrounding the coronation of Emperor Leopold II in Frankfurt in October of 1790. Ever since, this concerto has been known as the Coronation Concerto.
Wolfgang Mozart (1756-1791): Piano Concerto No. 26 (Coronation); Jenö Jandó, piano; Concentus Hungaricus; Mátyás Antál, conductor; Naxos 8.550209