According to Wolfgang Amadeus Mozart’s autograph entry in his personal work catalogue, the Verzeichnüß aller meiner Werke, the C major Piano Concerto K. 503 was completed on 4 December 1786. However, paper and watermark studies show that Mozart had already begun the work two years earlier, in the winter of 1784/85, and had then put it aside (Alan Tyson, Mozart. Studies of the Autograph Scores, Cambridge, Mass., 1987). For the Advent season of 1786, Mozart planned to hold a cycle of four new subscription concerts (called “academies”) at the Trattnerhof Casino, for which he apparently took up the C major concerto again and completed it. He gave the first performance himself, most likely on Tuesday, 5 December 1786; however, there is no documentary evidence for this concert. A further performance of the work may have taken place at the Kärtnertor-Theater on 7 March 1787 within a subscription concert of the pianist Maximiliana (Marianne) Willmann, who reportedly took lessons from Mozart. Although we do not know exactly which concerto she played there, it is likely that it was the new one in C major K. 503. Later, while travelling to Berlin, Mozart organized an “academy” together with Josepha Duschek at Leipzig’s Gewandhaus on 12 May 1789. On the program was the C major Concerto (along with the Piano Concerto K. 456, the Piano Fantasy K. 475 and the two soprano scenas K. 505 and 528). Mozart’s primary concern seems to have been to present a new, unpublished work to the Leipzig public. But the choice of K. 503 is also a clear expression of the special esteem in which he held this work, the longest of all his concertos.
Apart from the very neatly written autograph, which is typical of Mozart, a sheet of sketches to K. 503 has also survived. Under the heading “Mittelgedanken” [middle ideas], Mozart jotted down sketches for several passages from the first movement of the concerto. One of them concerns the passage between the first solo section and the following orchestral tutti (at measures 96ff.), which is crossed out in the autograph and newly written out on the following page. This again disproves the often advanced theory that Mozart always produced his autographs in one sitting and directly “from his head,” and that his works more or less simply “flew down” to him. Indeed, the sketch documents the enormous intellectual effort that Mozart put into writing his scores.
K. 503 was not published during Mozart’s lifetime and thus shares the fate of the majority of his piano concertos. The composer himself had only four of them published, K. 413– 415 and K. 450. He apparently considered the concertos as exclusive works, which he kept “for myself or for a small circle of music lovers and connoisseurs (who promise not to let them out of their hands)” (letter of 30 September 1786 to Sebastian Winter, the valet of Prince von Fürstenberg in Donaueschingen). K. 503 was one of the last piano concertos to be printed; it was published privately by Mozart’s widow Constanze in 1797. As emerges from a letter to the Offenbach publisher Johann André, she had been planning the publication since 1795 and ultimately had the work engraved at her own expense. The edition is dedicated to Prince Louis Ferdinand of Prussia and mentions (in Italian) on the title page that it has been published at the widow’s expense and is available at all fine music dealers. Details on the particular importance of this edition and the divergences from the autograph found within it may be found in the „Kritischer Bericht“ at the end of this volume.
I am very grateful to the Staatsbibliothek zu Berlin – Preußischer Kulturbesitz for having kindly supplied copies of the autograph and sketch sheet, as well as of the first edition.

Berlin, Spring 2011