That when performing the music of a "good" composer, you have to be very involved, tell a story, have your own ideas, give it something extra to make the audience understand. But when performing the music of a "great" composer you have to be selfless, removing all technical obstacles in order to perform the music as purely and faithfully as possible. You have none of your own ideas, no self, no ego, only the truth of what is on the page. You cannot add anything or take anything away.

If someone invited you to a meal at your very favorite restaurant (they pay), but you hate them, would you go?