I had just finished reading "This is Your Brain on Music," in which I learned that "the story of your brain on music is the story of an exquisite orchestration of brain regions, involving both the oldest and newest parts of the human brain," according to the author Daniel Levitin, a musician and neuroscientist. I had read that the best composers intentionally violate our expectations and that this pleases the part of the brain involved in motivation and reward. We thrive on the melody that goes up when it should go down, on the sudden pause.
And then I got in the car and turned on the radio. It was Bach's "Brandenburg Concerto Number Four," the third movement, presto. I reached down and turned up the volume. I've listened to this piece hundreds of times. I can visualize the album cover of the complete Brandenburg Concerti (in vinyl, of course) that Dad bought when I was in high school. There's one note that has always shaken me to the core. The violin and recorders are skittering all over the higher registers and there is an almost runaway-train cacophony of sound – when the cellos boom in with their final version of the melody. They hold the first note of that run slightly longer than they need to, as if to say, this is how you do it, folks. This is it. It's not what we expect at this point in the piece, and that's why it's thrilling.
Bach has a few more tricks up his sleeve, though. Three times near the end of this movement the sound comes to a complete halt. You don't expect these caesuras. But there they are, and they add a humor and lilt to the conclusion. When the sound stops, I can feel the pulse inside the silence.
I enjoyed reading the book; it helped me understand why I love melody and rhythm and timbre. But better than the book is the music itself.