Gilberto is trying a new reed. Sue is playing clarinet instead of soprano sax. A different bass player is sitting in. It is Wednesday, the middle of the week. At showtime, it doesn’t matter how many hours you practice, how much theory you know, how many times you have played a song. Live jazz is irrevocable. You can’t erase what you play, You are the bottom line. When the light turns green you play. When a song is over, it is over, except for a few bars that resonate in hearts that causes people to whistle your melody as they walk home in the dark.