I was kind of going off on a speculative tangent on that last sentence. I was wondering if that feeling was somehow reward-system related, and would fuel a musician's drive to excel. Like they try to play better and better to achieve that euphoria which only comes on when they do better than they ever have, with diminishing (dopamine?) returns, but, as a side-effect, increasing their practical talent to ever higher levels. So the musical prodigy over time becomes motivated more by the tangible rewards (fame, increased income), which will never compare to the feelings that made him choose that path in the first place. It would apply to many careers if it was a valid theory.