TB: Actually, you've raised something very important with that question, and that's the role of the producer. Once the multitrack tape recorder had been invented, the producer became absolutely central.

I quoted a producer in my book who said that he gets the pop musicians into the studio, he records all day, they go home, and then he changes absolutely everything that they've done.

DJ: So they're really just providing raw material?

TB: That's right. In certain kinds of music, the person who mixes the music is absolutely crucial.

DJ: That's the real artist, in a sense?

TB: Yes.

IB: If you think about Handel, who famously pilfered an almost unidentifiable number of musical ideas from other people, this seems like a similar thing, but maybe with pop music we're locating the musical genius in the wrong place. Maybe we're using the language of classical music or Romantic music to describe pop music, and maybe it's the wrong model.

TB: Well, the language of Romantic music does actually work quite well. A lot of the kind of things that you find Bono saying for example, could have come straight from a Romantic musician. Some of what he has said about the creative process could have been said by Franz Liszt.

IB: But if you look at the Beatles' music, it's a very unfamiliar model for a classical musician. Lennon and McCartney were definitely most successful as composers when they were working together, and I don't think that they produced anything as individuals that's as interesting as what they produced when they were bound together with their producer. And that's not a model that we really find with classical music. We have the lone genius instead.

TB: That's a very good point, and brings the producer back in again, because every account of the Beatles' recordings of the 1960s - especially after they'd made that turn towards much more ambitious music, having met Bob Dylan - shows that George Martin had a very important part to play in putting it all together. Sergeant Pepper is, I think, regularly voted as the most influential album of all time, which was in part manufactured in the studio by George Martin.

DJ: Can I bring in another element of this, which is the idea of music as a substitute for religion? You see that already beginning with Beethoven, and the idea of the genius. By the time of Wagner, it's quite far developed. But all of these musicians were living in a society where there was real religion in the background, creating the intellectual framework within which they worked. We're now living in a world where institutional, organised religion has been marginalised, and instead people live in a world of "mind, body, spirit" - those sections in bookshops with all kinds of weird stuff. It's almost as though music has become a substitute for religion. I wonder what you think about that.