The history books just say that Princess Celestia banished Nightmare Moon for a thousand years, and only that. But there is so much more to that story than just that. Nopony alive remembers what really happened a thousand years ago; nopony except Princess Celestia. It is a story that she refuses to speak of, and by her own personal decree the true story was buried by what is now written in every book. She tries to keep the story as simple and subtle as possible, but there is so much more that happened than what she admits.