In reply to aln:
> Thanks for that reply, that's the kind of thing I was looking for. I can see how they're important, but is "genius" maybe taking it a bit far?
The thing is, controlling tempo, dynamics, balance, phrasing etc doesn't sound like a massive thing ("okay, we'll play this one a bit faster with more clarinet..."), but in the course of a symphony, any of that stuff can vary at almost any time, which actually translates into enormous numbers of little tweaks over an hour or so of music. And a great conductor understands on some level the impact that any one of those little tweaks can have on the drama, the emotional impact and the structural integrity of a dense, complex piece of music, and can pull them all together (and communicate them to the players) to bring something out of the music that a less good conductor will fail to find.
I'd say that doing that well constitutes "genius".
Post edited at 11:49