“To make music” is only the beginning of the definition of your role in each of the settings you name; the rest of the definition must address your relationship with other players and the complexities of the music. In each setting, your role is somewhat different because of the kind of music-making and the forces the composer chose to express his ideas. It is overly simplistic to compare a solo recital, a string quartet, and a late romantic symphony orchestra; it suggests that whether Beethoven chose to use one or four or 60 instruments is somehow meaningless with respect to what individual musicians do, and I don’t think that’s the case.

When you get 50 or 75 or more than a hundred people involved in an effort, leadership is essential—not to honor someone’s ego or authority for authority’s sake, but because of (1) the practical difficulties of coordination and balance and (2) the practical impossibility that so many people would actually “vote” for the exact same interpretation of every bar. (Consider opera, and this point becomes even more obvious.)

The role of the conductor, then, is to set a goal and lead musicians toward achieving that goal. And that involves communicating, giving direction (coordinating, balancing), asking the right questions, solving problems, and listening. Naturally, I’m interested in the opinions and ideas of the key players (e.g., the concertmaster’s thoughts about bowing) and those of anyone with a substantial solo passage.