In the early 1770S Mozart took an interest in arranging other composers' works by transforming sonatas by J. C. Bach into concertos; a few years before he had attempted a similar feat on movements by C. P. E. Bach, Raupach, Schobert, Eckard and Honauer. He also wrote cadenzas for concertos by J. S. Schroeter in around 1774. It is possible that Mozart could in this manuscript, in a similar way, be adding his own particular stamp to a work by another composer, and it is likewise possible that the composer could be one of those mentioned above.
It seems unlikely that it is a work of transcription of Mozart's early years ( Einstein) or of his Viennese years ( Schmid).
Whether the basic musical material of the work is by Mozart or not, it is almost certain that the decorative passage-work is by him, and may perhaps have been written down after improvising at the keyboard. Indeed, it is possible that the whole composition may have been conceived by Mozart as a result of extemporisation.
A. Einstein, L. v. Köchel, Chronologisch-thematisches Verzeichnis der Werke W. A. Mozarts, third edition, with supplement, [ Ann Arbor,] Michigan, 1947.
W. Plath, "'Beiträge zur Mozart-Autographie II: Schriftchronologie 1770-I780'", Mozart-Jahrbuch ( 1976- 1977), 131-173.
E. Schmid, "'Neue Quellen zu Werken Mozarts'", Mozart-Jahrbuch ( 1956), [35-45, here] 44-5.
Sotheby's estimate of the market value of the manuscript was sound, for, in the event, it fetched £38,500, purchased for the library of the Mozarteum, Salzburg.
In general, Sotheby's description of the manuscript and its contents is on the mark, but more can be said about both. I shall deal first with the provenance and date of the manuscript, then with the 'source' piece that Mozart was ornamenting, and finally with the nature of those ornaments.
When Ernst Fritz Schmid published a small, blurry facsimile of the autograph manuscript of K. Anh. A 65 in the Mozart-Jahrbuch for 1956, it was in the possession of Dr Joseph Wolter of Berlin. Its earlier whereabouts have____________________