Once music ceases to be ephemeral - always disappearing - and becomes instead material... it leaves the condition of traditional music and enters the condition of painting. It becomes a painting, existing as material in space, not immaterial in time.
Painting, I think it's like jazz.
At the beginning of the 20th century, the ambition of the great painters was to make paintings that were like music, which was then considered as the noblest art.