s thought to reach back to 500 BCE, each tree contains a dryad, or magical tree spirit. Celtic Astrology, based on the mystical tree calendar in which the tree dryads represent the spiritual nature in human beings, will help you gain a new understanding of yourself and of others. All you need is the day and month of birth to find the corresponding tree sign to enhance the dynamics of your inner world: emotions, feelings, spirituality, and the subconscious mind.