~Watchtowers/Guardians/Quarters~
Quarter calls are designed to call only that energy you will allow in your magick circle. For all others, there is a No Trespassing sign. Nothing can come into your circle unless you, yourself, invite it, which is why there are so many different types of quarter calls that address various kinds of energy. There are calls that invoke the elements, angels, totem animals, deities of a particular pantheon, dragons, airts, winds, the dead, ancient archetypes, one's lineage, and/or the Watchtowers (stellar/ceremonial).
The quarter call creates a one-way passage into the circle for that which you have called to enter. It must wait in the circle until you are finished, and you must provide a way home for that energy. Therefore, you can't forget to release the quarters when you are done. Think of it this way: it's like asking your best friend to meet you at a party. She says, "That's cool, but I don't have a ride." You tell her that's not a problem, you'll provide the transportation both ways - that's the essence of a quarter call. You agreed to bring the energy in, and it is your responsibility to make sure that the energy returns to whence it came. There's no "Gee I forgot" allowed!
'The Ultimate Book of Shadows for the New Generation Solitary Witch' by Silver RavenWolf
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In early Stellar Cults of Mesopotamia there were four "royal" Stars (known as Lords) which were called the Watchers. Each one of these stars "ruled" over one of the four cardinal points common to astrology. This particular system would date from approximatelt 3000 B.C. The Star Aldebaran, when it marked the Vernal Equinox, held the position of Watcher of the East. Regulus, marking the Summer Solstice, was Watcher of the South. Antares, marking the Autumn Equinox, was Watcher of the West. Fomalhaut, marking the Winter Solstice, was Watcher of the North.
Towers as a form of worship were constructed bearing the symbols of the Watchers, and their symbols were set upon the towers for the purpose of evocation. These towers were called Ziggurats (cosmic mountains) and were said to have been 270 feet high. In part they served as primitive astronomical observatories, and were built with seven terraces representing the seven known planets of their era. During the "Rites of Calling" the Watchers' symbols were traced in the air using torches or ritual wands, and the secret names of the Watchers were called out.
'The Wiccan Mysteries' by Raven Grimassi