Beethoven is the first composer to represent the complex process of memory-not merely the sense of loss and regret that accompanies visions of the pa… - Charles Rosen

The piano is the only keyboard instrument in which one can grandly vary the effects of the harmonics or overtones of a chord at will by balancing the sonority in different ways.

For Beethoven, music was still shape, realized and inflected by instrumental sonority: other realizations may be as absurd as arrangements of the Hammerklavier, for example, always are, but the musical conception takes precedence over its realization in sound. The sonority serves the music. For Schumann, however, as for Chopin and Liszt, the conception was worked out directly within the sonority as a sculptor works directly in clay or marble. The instrumental sound is shaped into music.

Inaudible music may seem an odd notion, even a foolishly Romantic one—although it is partly the Romantic prejudice in favor of sensuous experience that makes it seem odd. Still, there are details of music which cannot be heard but only imagined, and even certain aspects of musical form which cannot be realized in sound even by the imagination.