Be a storyteller, not a preacher. That was novelist Walker Percy’s legendary advice to a young Walter Isaacson. One he takes to heart in his work as a journalist at Time and CNN, and as a biographer of creative genius across the centuries—and in trying to capture someone as volatile as Elon Musk. He reflects on the challenges of holding the complexity of a character in his mind—and the minds of readers—in the modern age, when everyone just wants to know if the emerald mines were real.