Today’s composer of the day is Olivier Messiaen.
Frenchman Olivier Messiaen’s music is difficult to find in America, though it is still performed with relative regularity. His students, however, are well-known and widely respected (Pierre Boulez, Karlheinz Stockcockblochen, Iannis Xenakis).
He had a disease, which, one assumes, helped make his music extremely colorful. He had synaesthesia.
Synaesthesia is classified as a disease in which specific sensory input (e.g. a sound) triggers involuntary responses from another, second, sensory pathway (e.g. vision). In other words, sounds can trigger visual sensations. There are many kinds of synaesthetes, including number-letter » color associations, number » form (object) associations, sound » color, word » taste, and the ever rare sound » taste.
In the case of the sound » color form, specific pitches or harmonies create a sensation of specific colors or patterns of colors.
For a composer like Messiaen, his sound » color form of synaesthesia translated into vibrantly “colorful” music. A devout Catholic organist, he developed his own highly personal symbolic system of composition with color. I forget the exact chord which symbolized the blood of Christ, but I assure you it's a good one.