This composer set a poem describing "Black, giant butterflies descend[ing] 
This composer set a poem describing "Black, giant butterflies descend[ing] upon the hearts of men" in a passacaglia movement, titled "Night". That work by this composer concludes with a soprano singing of being seduced by an "ancient fragrance". A namesake ensemble consisting of flute, clarinet, violin, cello, and piano was inspired by that melodrama by this composer, which is based on the poems of Albert Giraud, and which makes heavy use of a half-speaking, half-singing technique called Sprechstimme. A poem about a woman admitting to her lover that she is carrying another man's child inspired a string sextet by him, based on that Richard Dehmel poem. For 10 points, name this composer of Pierrot Lunaire and Transfigured Night, the founder of the Second Viennese School.
This composer set a poem describing "Black, giant butterflies descend[ing] upon the hearts of men" in a passacaglia movement, titled "Night".
Arnold Schoenberg