The document discusses literary theory and how different perspectives, or "sunglasses", can lead to different interpretations of the same text. It uses the example of the nursery rhyme "Little Miss Muffet" and shows how a sociologist, militarist, demonstrator, editorial writer, and child would analyze the rhyme differently based on their own lens. Literary theory provides deeper understanding of texts by showing there is no single correct analysis and encouraging readers to think freely about what they read without confinement to one interpretation. The document introduces five major approaches to literary theory: historical criticism, reader-response theory, new criticism, feminist criticism, and Marxist criticism.