Good conductors use an intensity of concentration needed in very few other jobs. This enables them, often in an uncanny way, to project thoughts and feelings to the musicians. Arthur Nikisch had a reputation for mesmerizing an orchestra. Someone who played for Arturo Toscanini told me he sometimes felt a strange sensation, like a hand pushing down on his head, when the maestro wanted him to play more quietly.

It's infectious—the players are drawn to concentrate as deeply as the conductor. I remember a violinist telling me after a rehearsal in Holland that he worked as a part-time hypnotherapist. “So you may be interested to know,” he said, “that when you conduct, you put the orchestra into a light trance.” I was somewhat taken aback, but in the end I decided it was probably a compliment.

An audience picks up a conductor's concentration and involvement. People sense that something important is going on and want to be part of it. If they don't feel that way, they'll get very little out of a concert and become restless or even noisy.