Just as a novel might start with a preface and a nonfiction book might include an introduction to the history of the topic, an academic work may begin with a prolegomenon. It’s a specific type of formal essay that introduces a longer work. For example, a professor could write a prolegomenon that’s published at the beginning of a compilation of a writer’s body of work. “Prolegomenon” comes from the Greek “prolegein,” meaning “to say beforehand.”