Book of Mirrors
The Book of Mirrors is a personal journal kept in some wiccan traditions. If the Book of Shadows is a collection of the magical knowledge of a witch, the Book of Mirrors is a collection of opinions, feelings, reactions, and thoughts on magical and mundane events in the witch's life.
GeneRally, the Book of Mirrors is kept as a log of reactions and reflections on magical workings of the witch. After a spell worked in the Book of Shadows is completed, the witch studies its perceived effects and records these perceptions in the Book of Mirrors. This provides the witch with a foundation from which to reinterpret the meaning and utility of the spell that has been cast.
Use of a Book of Mirrors is not a part of Gardnerian Wicca or many of the mainstream offshoots it has produced. However, it is a growing tradition among some of the more obscure traditions of wicca that are further removed from the Gardnerian tradition.