In 1966, two of the greatest composers of the 20th century met to discuss the dramatic change in the audiences they were encountering at jazz and classical concerts; how, in other words, the audiences for different kinds of music were becoming less tribal... 

Partial transcript:

Bernstein We really share the same audiences to a much greater extent than we used to. I mean, as you say, you have your own audience... well, that used to be true, and I suppose 'our kind of music' (if you can say such a thing), used to have its audience – but now you can't tell them apart any more. I mean, the same kids and the same excited people come to hear you as come to hear me. And that's something new.

Ellington It's getting to the point now where the modern contemporary composer and the guy who is supposedly a modern jazz composer - they all come out of the same conservatories.

Bernstein Exactly.

Ellington And it's very difficult to find a place to draw a line.

Bernstein Well, you were certainly one of the pioneers of that...

Ellington Oh yeah, but I didn't come out of a conservatory!

Bernstein No, but you were one of the first people who wrote so-called 'symphonic jazz'... Maybe that's the difference between us - you wrote 'symphonic jazz' and I wrote 'jazz symphonies'.

(A hat-tip to Philip Clark for drawing our attention to this video)