[fiddler]

as long as it's a *good* orchestra, basically the orchestra acts as the musical instrument for the conductor, "the artist". that's sorta the ideal-world scenario. like for example berlin phil are just about good enough (ok, so they're like the one of the best in the world period) to be able to be at that level where a top-class conductor can walk in and just make music just the way he pictures in his head.

there's more to it than that (enter soloists, singers...) but basically, the conductor calls the shots. he gives the musicians a "vision" to strive for. it's the players' responsibility to take care of the mechanics, including good ensemble etc.. ideally a conductor never has to worry about whether the winds are playing in tune, or whether the first violins are rushing ahead of everyone... but that "ideal" situation only happens in the best-of-the-best orchestras. definitely not the case with toronto symphony sadly... (they suck)

as for whether or not the baton waving actually matters in the actual concert, well not neraly as much as the stuff that happens in the background. sure the conductor might have a moment of inspiration and decide to take everybody by surprise (we all are hoping he doesn't do too much of that..), but i'd say most of the "plays" are created during rehearsal.

just the same as if you were just a solo pianist... all those musical ideas, technical perfection, all of it is "created" in the practise room. the concert is just an exhibition of all the hours of work the musician's put into the music.

of course that isnt' to say something magical doens't happen in a (good) live concert situation, stuff that doesnt' happen in rehearsals. its' impossible to explain properly... it's easy to picture a piano soloist having a moment of inspiration on stage and creating music like he's never made before. but sometimes that same very thing can take hold of an entire symphony orchestra. and in those moments the conductor can usually just stop beating, and the music will just flow out naturally without any more help required. it's the conductor that leads the musicians to that "aha!" epiphany moment, which hopefully takes place IN CONCERT rather than be wasted in the dress rehearsal!

so... no easy answer to this question!