The composition of Un ballo in maschera caused Verdi many problems. What began as an opera called Gustavo III was subject to censorship by the Neapolitan and Roman authorities, so it's libretto, location and title all changed. The subject, however, is still the murder of Riccardo (Gustavo) at the masked ball, couched in a musical language in which the seriousness of Italian opera is infused with French vivacity. The opera's structure is carefully symmetrical in the great terzets, and the themes of duty, pleasure, drama and humor are rendered with masterful clarity.