A novelist must create characters, as well as a plot that moves the story forward, but all of this must exist within a fictional world. How do writers create such a world? Most writing teachers tell their students to write what they know. My great teacher Albert Guerard, who taught at Harvard for twenty years and then at Stanford for twenty more years, told his students something quite different: Write what you can imagine. This was hugely freeing to his students and to me. A writer did not have to write about his or her own life, which might be small and uninteresting. In fact, the whole world is open to a novelist. Imagination is everything.