Sibelius in Color

My son's youth orchestra just performed Sibelius' First Symphony and blew everyone in the audience away. Here is a description of the piece by Robert Bagar, quoted in the program notes, that sums up what I heard:
"...The young composer pours great melodies into his work, melodies that sing with the exultant joy, melodies that rise and fall with tremendous intensity, and also melodies that are nostalgic and mellow and suffused with a tender pathos. There are grace and lightness in the music as it comes rushing to the creator's pen. There are also wild, barbaric shouts, outbursts of tremendous passion, raging unbridled utterances that hurl themselves forward like the roar of giants winds."
Sibelius was one of the rare people who sees musical notes as colors (synesthesia). Experiencing this rich, complex piece just as sound was quite enough for me. I think it must have been hallucinogenic--maybe even frightening--to "see" it as well.
After the concert, my son reflected that a lot of the music we hear today Sibelius would find pretty strange. I said, "Don't you think he'd be pretty amazed that his music is still being performed all over the world in lots of different places by lots of different kinds of people?"
"No," he answered. "Composers are pretty vain."
Maybe he's right. Maybe one has to be to write music like that.