Not only do Magic circles (or mandals) provide protection against dangerous spirits but they shield you from the eyes of other human beings. Since the ancient sages mostly cast their circles outdoors, the circle gave them privacy. It is said that if a person came upon you during your operation, they would see instead a great mountain, lake, or some other physical obstruction giving them no choice but to chart a course around you.
Above; An Assemblage of Ceremonial Magic Ebenezer Sibly (1751-1800), was a famous 18th century British astrologer, best known for his book, A New and Complete Illustration of the Occult Sciences (1787), later renamed A New and Complete Illustration of Celestial Sciences of Astrology. It is devoted primary to Astrology however the final book, deals primarily with ceremonial magic. Much of the material was taken from the expanded 1665 edition of Reginald Scot's Discoverie of Witchcraft, including the engravings (seen above) which were redrawn from those found throughout Scot’s work. The figure of the conjuring knife, the figure of the Circle, and the figure of the breastplate (or in Sibly, “a great character”) are all specified for “An experiment of Bealphares” in ascot. From: A New and Complete Illustration of the Celestial Sciences of Astrology, 1817
