When we got to the part where we had to improvise an argument in a poetic language, I got cold feet. "I can't do this," I said. "I don't know what to say." "Say anything," he said. "You can't make a mistake when you improvise." "What if I mess it up? What if I screw up the rhythm?" "You can't," he said. "It's like drumming. If you miss a beat, you create another." In this simple exchange, Sam taught me the secret of improvisation, one that I have accessed my whole life.