Alexander Scriabin (1872-1915)

Scriabin experimented with the construction of chords in intervals of a fourth instead of, as was the rule in traditional harmony, a third.  A structure he designed and frequently incorporated was his "mystic" chord, built in fourths -- C  F#  Bb  E  A  D.  He was one of those who ushered in new conceptions of dissonance and tonality.  His fame rests on several grandiose symphonic poems of post-Wagnerian cast, such as the "Poem of Ecstasy" (1908), as well as ten piano sonatas and a variety of short piano pieces -- preludes, etudes, mazurkas, and the like.