Here is some more stuff about Synesthaesia:
Scriabin and Rimsky-Korsakov freely associated with colours when they composed. To Rimsky C major was white and A major was rosy. To Scriabin C major was red and A major was green. One would imagine that it was all personal. But there was a surprising amount of agreement between them: Both associated E major with blue (R: sapphire blue - S: blue-white). Ab major was purple (R: grayish violet - S: purple violet) D major was yellow.
Writers were also into it: Nabokov, Faulkner, Virginia Woolfm Huysmans, Joyce, Dylan Thomas. Baudelaire actually wrote a poem on sense correspondences.
And the Symbolist movement in art was really about synesthesia.
And of course, a bit of mescalin and LSD can really help - just read Aldous Huxley's The Doors of Perception.
And come to think of it, this is really what Disney's fantasia is all about: calssical musica and colour

Apparently synesthesia is hereditary.