4. A statement of simple fact laced with significance.
Because readers don’t read backward, it’s possible to bury a key piece of a story in an opening so that, by the time it becomes relevant, the reader has forgotten it. Agatha Christie mysteries do this often. The key to solving the crime in Murder on the Orient Express, for example, is embedded innocuously in the opening sentence. So is the key to the heroine’s psyche in Margaret Mitchell’s Gone With the Wind, the opening of which explains, “Scarlett O’Hara was not beautiful. …”