A sensational finding provided the impetus for this new edition. In autumn 2014 a hitherto unknown Mozart autograph of the famous Piano Sonata in A major (with the enduring “Turkish March”) surfaced in Budapest. After a painstaking study of the manuscript and a meticulous comparison with all of the other sources, G. Henle Publishers is now issuing the first definitive Urtext edition of significant parts of this masterpiece (the new autograph does not contain the complete sonata). It must be said that there are serious deviations from the musical text as we know it. So we are proud to be able to say that it is not possible to seriously study this sonata without consulting our Urtext edition.