On one stave, for a small instrument, the man writes a whole world of the deepest thoughts and most powerful feelings. If I imagined that I could have created, even conceived the piece, I am quite certain that the excess of excitement and earth-shattering experience would have driven me out of my mind.

Discussion of the Chaconne in Bach's Partita for Violin #2. Litzman, Berthold (editor). "Letters of Clara Schumann and Johannes Brahms, 1853–1896". Hyperion Press, 1979, p. 16.