The Past is not unchanging. Often we learn new things that change our understanding of what past events truly meant and create new appreciations of how things really fit together. A Story that focuses on The Past, may be much more than a documentation of what happened. Frequently, it is a reevaluation of the meaning of what has occurred that can lead to changing one’s understanding of what is happening in the present or will eventually happen in the future.
From the Dramatica Dictionary