In February, 1903, a nineteen-year-old Austrian military cadet named Franz Xaver Kappus received a letter whose contents, he hoped, would teach him how to live. “The envelope,” he later wrote ...

Aged barely 13, Franz Xaver gave his highly anticipated first public concert in a packed Vienna hall. Critics praised his performance but also warned the boy not to rest on his laurels.

Franz Xaver Süssmayr (1766-1803), Mozart’s pupil, was asked by the composer’s widow, Constanze, to complete the work, but his efforts have often been criticised as unworthy of his teacher.