Many of our attitudes, superstitions, and uneasiness concerning mirrors date back to ancient times.  The first mirrors were made of polished stone, copper, and silver.  Because these materials were often difficult to smooth and polish, the reflections in these mirrors were often dark and distorted, giving an almost unsettling appearance.  It probably would have been a little eerie to gaze into, and no doubt had another worldly and spooky feel to it.