In his introductory lectures, Leon Botstein is almost always engaging and enthusiastic, except when, to make an instructive point, he discusses music he knows to be inferior , and then he is at least amusing. However, before the Sunday matinee of Taneyev's Oresteia, he conveyed a certain Cheshire Cat-like excitement, as if he had something really exceptional in store for us. The air in and around the Fisher Center was charged, and one could feel it. We were not disappointed.