As a Wiccan, you will probably want to keep a written record of your spiritual path. A Book of Shadows and a Book of Mirrors serve different needs. Your Book of Shadows is like a cookbook which you fill with recipes on how to do things. Your Book of Mirrors is a personal journal where you might write the date, the recipe that you tried, and your feelings about the outcome.
Traditionally, a witch’s Book of Shadows (also known as a grimoire) held all the spells she acquired or created throughout her lifetime. The term “book of shadows” comes from the historical need to keep such a treasure secret or risk having evidence of one’s ability fall into the hands of witch hunters.
Think of your Book of Shadows as a collection of how-to articles. Just as if you were writing a cookbook or an encyclopedia, you organize your articles by topic, not by date. You do not clutter the pages with personal reflection other than a few succinct tips. Save dates and emotional expression for your Book of Mirrors.
The Book of Shadows is not just a place to write down your spells. If you are a Wiccan who does not practice witchcraft, you have other things to include, such as recipes and tips on herb gardening, divination, candle-making, creation of essential oils, and more. You can use it to organize the ceremonies that you design for sabbats, esbats, and the milestones of life.
Meanwhile, your Book of Mirrors is your personal diary. The term “book of mirrors” reflects its purpose in showing you an evolving picture of yourself. As you try out the how-to articles from your Book of Shadows, you can describe the results in your Book of Mirrors. For example, include in your Book of Shadows the instructions on how to use a pendulum for divination. Use your Book of Mirrors to store actual predictions made with the pendulum, which you can check later for accuracy. You can also use your Book of Mirrors to record your nightly dreams and their interpretations.
Before the invention of the printing press, a witch needed her Book of Shadows. Nowadays, with how-to books everywhere on every aspect of witchcraft, it is becoming obsolete. It is easier for new witches and Wiccans to keep a reference library of purchased books or to go online to search for instruction. If they want to customize a spell, they might attach physical or electronic annotation to their books.
I urge new witches and Wiccans to create their own Books of Shadows anyway. Your Book of Shadows can be on your computer or written in a blank book. The important thing is to centralize your personal knowledge in one spot where you can refer to it and customize it. With time and attention, your Book of Shadows absorbs enough of your personal energy to become an object of power in its own right.
Meanwhile, the Book of Mirrors shows no signs of going out of style. It is an excellent way to document your spiritual path, but it can serve a deeper need. With it, you can communicate with your future self, which will read back on your words. Everyone needs someone to talk to, and many solitary witches and Wiccans have no one with which to discuss spiritual concerns. Your Book of Mirrors can meet that need, and be an invaluable addition to your spiritual practice.