Mozart. A Musical Joke K.522 full score

Ein musikalischer Spaß in German.
This is a sheet music of a full score of the divertimento for two horns and string quartet written in 1787. The composition consists of many places which are written in a way, as if it were composed by incompetent composer. Some gaffes in harmony and rythm, for example. But, as everything by Mozart, the music is just amazing - light and clear.

Life of Mozart by O. Jahn. Translator's note

CONSIDERABLE doubt has existed in the mind of the translator as to the proper English equivalent for the word "clavier" throughout this work. Clavier is a generic term in German, and is used to denote any keyed instrument, whether harpsichord, clavichord, or pianoforte. Mozart's compositions for the clavier are equally available for all these instruments, and in his early years he performed indifferently on the harpsichord or clavichord. His first introduction to the pianoforte was at Augsburg, in 1777, and he did not become familiar with the instrument until after his settlement in Vienna in 1781.

Life of Mozart by O. Jahn. Preface to the English edition (1882)

I have been asked to say a few words by way of welcome to the translation of Jahn's Life of Mozart, and I do so with pleasure. The book has been long familiar to me, and I regard its appearance in an English dress as an event in our musical history. It will be a great boon to students and lovers of music, and it shows how much the study of music has advanced among us when so large and serious a work is sufficiently appreciated to repay the heavy expense attendant on its translation and publication. The book itself is what the Germans call an "epoch-making work." The old biographies of musicians, such as Forkel's Life of Bach (1802) and Dies's of Haydn (1810), are pleasant gossipy accounts of the outward life of the composers; but they concern themselves mainly with the exterior both of the man and his productions, and there is a sort of tacit understanding throughout that if the reader is a professional musician he will know all about the music, if he is an amateur it is altogether out of his reach.