Unlike the composer/conductor duality which has since Wagner, or better yet Lully, given us the genius of Mahler, Webern, Bernstein, Boulez, Pendereski, and now John Adams and Salonen (but also, lamentably, the insatiably vapid music of John Williams and the "authentic"-a-la-Robert-Craft Stravinsky ...
With the possible exception of Lutaslowski's chains, Boulez's tropes, Cage's bastardized I Ching, Riley's string modules, Stockhausen's texts, and my own admittedly trite rip-off of those "chose your own ending" books, there has been no significant formal innovation in contemporary Western art music...
I should certainly hope that even the most casual student of music history can in fact trace, and most acutely at that, the growth and maturation of his subject in the midst of a near millennium's worth of development. (If for some perspectival cataract he cannot, then perhaps his musical prowess is...