Modest Mussorgsky's 'Boris Godunov' stands out among the major works of the opera repertoire in having an extremely complex creative history. The original libretto, by the composer himself, was based closely on Pushkin's Shakespeare-inspired drama about the ill-fated Russian ruler. Mussorgsky completed the score in 1869, and submitted it to the committees of the Imperial Theatres. It was rejected, however, primarily because of the lack of a female lead and therefore a love interest, but Mussorgsky's unadorned style has also been mentioned as a reason. In 1871 the composer therefore reworked the opera extensively, adding new scenes and a female principal in the form of the Polish princess Marina Mniszek and changing the overall structure from seven scenes into a prologue and four acts.