J.S. Bach: Chaconne from Partita No. 2

Johannes Brahms, in a letter to Clara Schumann, said about the Chaconne:

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.