Synesthesia is a condition that occurs when an individual
who receives a stimulus in one sense modality simultaneously
experiences a sensation in another..
.. or, in the words of Lisa Simpson after drinking the water
ride sludge at the Duff Amusement Park ("The Simpsons", ca 1997):
Kandinsky was fascinated by the connections between color
and sound. His paining "Succession" (1935) is a great
example of "I dont know what it is but I recognize it."
If you know of a place on the web where the painting is
shown (lawfully), please let us know!