
Rosen examines how 19th Century composers extended the boundaries of music, and their engagement with literature, landscape and the divine.
A feature of notated music (which is what most of us mean when we say "[western] classical music") is that there can be things notated and not heard. Similarly, there are also different notations which correspond to the same sound. Notation is ambiguous, and this can be a source of both frustration (for the students) and invention (for the composers). Charles Rosen opens his book The Romantic Generation with a fascinating discussion about music which is seen and not heard which deals with this philosophical issue.
Of course this practice goes back much further. Composers have been playing with notation for a long time and it reached a peak of sophistication in the 15th century, as Emily Zazulia demonstrated in her PhD thesis and book[1]. This quality is obviously absent in musical cultures which do not rely on notation. I imagine to the outsider it appears as if the notation itself has taken on a life of its own to the detriment of the sounding music. Of course there is a certain elitism involved as well since explaining subtleties in notation is also a sure way of ostentatiously demonstrating one's erudition, which may explain why these kind of discussions are perennially popular here ;).
[1] https://global.oup.com/academic/product/where-sight-meets-so...
