Alexander Scriabin (1872-1915) was a Russian composer and pianist. He also created his own mystic religion believing that when all the arts and senses were united as one, the world would end in a total state of bliss. He envisioned his greatest work "Mysterium" as a week-long performance of music, dancing, with lights and smells taking place in the Himalayan mountains as a means of achieving this. He died before he could the performance could be realized.
Scriabin also experienced synesthesia - hearing musical notes as colours. One of his later orchestral works, "Prometheus: The Poem of Fire" incorporates a device known as a colour organ. It was a keyboard instrument played like a piano but projecting colours instead of notes. Remarkably, this was performed in 1910! In this work Scriabin uses what is called the Mystic Chord for the harmonic and melodic basis. It is a pitch collection of his own devising based on a 6 note scale.
As a young composer, Scriabin worshiped Chopin and many of his early works are very reminiscent of Chopin and romantic in nature. As he matured, he found his own vision and created a very unique tonal language that is still being studied by music theorists today.
Oh, and he was fascinated by insects; they were a big part of his apocalyptic vision. Here is Vladimir Horowitz playing Vers La Flamme. Listen especially in the second half to hear the bugs annihilating themselves in the flames.