Venanzio Rauzzini (1746-1810), Mozart's first Cecilio ("Lucio Silla"), was a famous Castrato, composer, sought-after teacher and was in constant correspondence with the great composers of his time. These Solfeggi written by the great master are excellent and methodical exercises as well as musically appealing. In addition to Mozart's own Solfeggien KV 393 they are probably the best source and basis for stylish and tech-savvy Mozart song.