This is the beginning of Bach’s Ciaccona, from his violin Partita in D minor for solo violin. It’s amazing. To me it has two meanings: One, it’s a relic from my time as a violinist in a pro classical orchestra.
And two, there’s the piece itself. For this, I’ll let Clara Schumann do the talking: “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.”