The Power of the Fiend (, Vrazhya sila) is an opera in five acts by Alexander Serov, composed during 1867-1871. The libretto is derived from a drama by Alexander Ostrovsky from 1854 entitled Live Not As You Would Like To, But As God Commands. The opera was premiered posthumously on 19 April 1871 (Old Style) at the Mariinsky Theatre in Saint Petersburg conducted by Eduard Nápravník. Among the performers were Darya Leonova as Spiridonovna and Mikhail Sariotti as Yeryomka. Although in many ways it is more far-reaching than Serov's previous two operas, this work was not a success. The title of the opera (taken from an appellation that Ostrovsky had applied to the fourth act of the projected libretto) has been translated in a number of ways: The Hostile Power, The Fiendish Power, The Malevolent Power, The Power of Evil, and so on. As an obsolete Russian phrase, it can mean simply "Satan" or "The Devil" (indeed, the Mariinsky Theatre renders the title of the opera in English as Satan). Part of the variety in translation derives from interpreting the initial word of the title. Вражий in Russian is an adjective from the noun враг ("foe" or "enemy"; obsoletely "the Fiend" or "the Devil"). In the case of this drama the title relates to the character Yeryomka. Composition history Although Ostrovsky originally agreed to act as librettist and proceeded to versify his prose play through the first three acts of the opera text, he declined to when the composer insisted on changing the happy ending of the play into a tragic one. Therefore, the remainder of the libretto was prepared by Pyotr Ivanovich Kalashnikov and Alexander Fyodorovich Zhokhov. If not for the delay caused by the rift with Ostrovsky, Serov might have completed the opera, but unfortunately the music of the final act was lacking at the time of his death. His wife, Valentina Serova, composed Act 5 supposedly using her recollections of unwritten sketches that Serov had played at the piano, and the composer Nikolai Solovyov assisted in bringing the opera to a performable state by orchestrating some of the music for Act 1. Despite a new edition of the opera completed by Boris Asafiev for a Soviet performance in 1947, The Power of the Fiend still remains well outside of the repertory. Roles (Note: Due to gaps in information from one source to another, this section combines data