Complex sentence: The Czech libretto was written by the poet Jaroslav Kvapil (1868--1950) based on the fairy tales of Karel Jaromír Erben and Božena Němcová; a Rusalka is a water sprite of Slavic mythology, usually inhabiting a lake or river.
Split into simpler sentences: The Czech libretto was written by the poet Jaroslav Kvapil (1868--1950) based on the fairy tales of Karel Jaromír Erben and Božena Němcová. A Rusalka is a water sprite from Slavic mythology, usually inhabiting a lake or river.