A childhood belief about mirrors

My mom has a curio cabinet with a mirror on the back, which reflects the contents of the cabinet. That mirror was always so clean (because it was behind a glass door) that it seemed to be doing more than just reflecting. All the other mirrors in our house weren't quite so shiny. Anyway, I always thought that the mirror harbored another world, an opposite, reversed world where things were different, but where there was a girl who looked just like me. I used to spend hours just looking so hard at the mirror, trying to figure out how to get inside. My mom thought I really liked the stuff in there -- antique glass, music boxes, that sort of thing. But really, I just wanted to trade places with my opposite, and see if the world on the other side was any better.