For whatever reason, on Thursday I only had one and a half cups of coffee. I had had a sleepless night earlier in the week, and didn’t want to risk another, so when I realized that it was late afternoon and that I had completely forgotten to make the second (and third) morning pot, I decided to go without. Figured I’d risk a groggy rehearsal in favor of a healthy sleep that night. That turned out to be an enormous mistake. I was playing with the Illinois Philharmonic , and the menu for that evening was The Chairman Dances , by John Adams, and while there’s not a technically difficult measure in the whole piece, it’s relentlessly hard to play correctly. The minimalist harmonies give you no help, and all of the entrances are off the beat unpredictably, and the subtly shifting rhythms require intense focus. And I didn’t have it. I had practiced the part, but not enough to pull it off with my brain drooping. I SOUNDED like a bad player. T...