FROM DISTANT TIMES, and in distant ways, up until modern times, practitioners of the sacred have worked in groups within a circle of protection. A circle has no beginning or end; hence, practitioners cast a sacred circle to represent the macrocosm and the microcosm and produce the thought form that exists to protect those working within the circle.
It can be seen as a container, keeping within its ring-pass- not the working energy and blocking without energies and entities that are unwelcome. Our world consists of vibrating sounds, lights and colours and we measure time in cycles with clocks, calendars, zodiacal wheels etc.
A circle, then, has been used for millennia and has the power of certain numbers. For the purposes of undertaking magical and sacred work, combinations of people, in particular formations, the circle has greater protections and ability to work with forces of regeneration and energy than individuals alone or in haphazard numbers. Hence, three, six, nine and the definitive end number twelve have special potency for working with spiritual, sacred energies, and this has been the case since Plato and before.
Twelve is the number of completion. Numbers have always had mystical significance, and a whole science was based around these significances. People believe numbers linked with the alphabet, the stars, and the constellations. The number twelve represented the hours of day and night, the months of the year, and the zodiac. Sumerian priests first divided the year into twelve months of about thirty days each, and their day had twelve units so the number twelve became the unit of dividing time….
The twelve prophets, the twelve patriarchs, the twelve tribes, and the twelve Apostles–each group has a certain occult significance, for each refers to the Divine Duodecimo, or Twelvefold Deity, whose emanations are manifested in the tangible created Universe through twelve individualized channels…
…As these 12 (the three substances, salt, sulphur and mercury) existing in the four worlds, as shown in the table, sum up to the number 12. As these 12 are the foundations of The Great Work (alchemical), they are called in revelation the twelve foundation stones of the sacred city.”
Here is a chart depicting the importance of Twelves in Vedic Wisdom.