Egregores
An egregore is essentially an artificially constructed spirit or entity in the astral plane, created by powerful individuals or the activities of collective groups. According to the Golden Dawn Glossary, egregores are: "A thought-form created by will and visualization. A group egregore is the distinctive energy of a specific group of magicians who are working together, creating and building the same thought-form or energy-form." A more complete definition comes from the occult society Aurum Solis, who define an egregore as: "An energized astral form produced consciously or unconsciously by human agency. In particular, (a) a strongly characterized form, usually an archetypal image, produced by the imaginative and emotional energies of a religious or magical group collectively, or (b) an astral shape of any kind, deliberately formulated by a magician to carry a specific force."

The statement "some ideas take on a life of their own" is the quintessential concept underlying the existence of egregores. Egregores are not restricted to magical societies (though these can be the most powerful sort), but political parties, environmental activist groups, churches, families, and even clubs and clique. An egregore grows by drawing energy from the members of the organization. Thus, the power of an egregore is entirely dependent on the will of the organization's members, and most are so week as to be negligible. Some, however, become exceedingly powerful (even dangerously so) and begin to psychically affect the members of the group, and sometimes even human events and history. The Ancient Greeks considered this to be the "art of Spirits and Entities, Cordey, pg. 7 creating gods", and indeed this may have been how many gods and demi-gods were created -- not by divine power, but by the mind of man. At such a point, an egregore is an egregore no more, and becomes a free entity in its own right. Even so, such beings still require the focus and attention of human followers, and will diminish (even die) otherwise. Needless to say, a great many egregores vanished with the rise of Christianity, though many of the egregoric deities were "converted" to saints and angels.

Individual egregores can also be created through magical ritual, or unconsciously by those of great will. Such personal egregores are weak compared to the egregoric deities, but can have considerable magical influence. The very act of casting a spell may create an egregore to carry out the action within the astral plane. Summoning spirits in magical ritual may also either create a new egregore, or link the magician to an older, preexisting egregore. For instance, the strange spirits cataloged in the Lemegeton (Goetia, etc.) may in fact be egregores -- they exist not because they have existed for all time, but because magicians in the Middle Ages began to use them in magical ritual. They still exist today because magicians continue to conjure them in the same way and for the same purposes as listed in the Lemegeton.