His important works include numerous short pieces for piano, ten piano sonatas, of which the fifth and ninth are most often played, and five symphonc works. One of them, entitled ''Prometheus: Poem of Fire'', includes a part for "color organ," an instrument purely from Scriabin's imagination, which projects color on a screen instead of sound. | His important works include numerous short pieces for piano, ten piano sonatas, of which the fifth and ninth are most often played, and five symphonc works. One of them, entitled ''Prometheus: Poem of Fire'', includes a part for "color organ," an instrument purely from Scriabin's imagination, which projects color on a screen instead of sound. |