Witches celebrate an Esbat every month on the full moon. Whereas Sabbats are celebrations, Esbats are seen as a time to work magic. They are on the full moon because it’s the time when the moon’s energy is strongest and it is the best time to cast spells of any kind. The word Esbat came into use today as a result of Margaret Murray’s writings. Murray wrote a book on witchcraft and its history in the early 20th century, which although it was discredited in the 1970s for manipulating evidence to prove her theories, her work was still very influential to the foundation of Wicca and the resurgence of other neo-pagan faiths.