Magic Circle

Performing magic rituals within a circle protects you - if the circle is properly drawn and inscribed - from whatever demons you might call up.

In Jewish weddings it used to be a custom for the guests to circle the bride and groom seven times, bearing lighted candles. This drove away demons, spirits of darkness.

Ritual magicians warn that some demons are devilishly clever in devising ways to get you to put a foot outside the circle. Those particularly horrible in appearance (or stinking, for there is a distinct odor of sanctity, it is said) might tempt you to flee. Stay within the circle, whatever happens.

Witches were supposed to wind up their spells by dancing in a circle. Because Satan is the Adversary, in black magic things are reversed (as in the Black Mass). So they danced widdershins, which is to ay counterclockwise.

Superstition looked at rings in the turf formed by underground fungi and imagined these were Fairy Circles, the little people's dancing places.

Circular depressions in fields of grain these days get all sorts of imaginative responses. But if a circle is more or less than nine feet in diameter, it is not a magic circle, and for magical purposes it must be drawn with the tip of a magical sword, so a very wide diameter is impossible

A fragment from:
The Complete Book of Devils and Demons
Leonard R.N. Ashley - Barricade Books - ISBN 1-56980-077-4(TP)