Nonphysical entities which exist in either the mental or astral plane. Each entity is created from the thought. Every thought is said to generate vibrations in the aura’s mental body, which assume a floating form and colors depending on the nature and intensity of the thought. These thought-forms are usually seen by clairvoyants; and may be intuitively sensed by others.
Theosophists and clairvoyants Annie Besant and C. W. Leadbeater placed thought-forms in three classifications: (1) the image of the thinker (see Bilocation); (2) an image of a material object associated with the thought; and (3) an independent image expressing the inherent qualities of the thought. Thoughts which are of a low nature, such as anger, hate, lust, greed, and so on, create thought-forms which are dense in color and form. Thought of a more spiritual nature tend to generate forms possessing a greater purity, clarity, and refinement.
Thought-forms can be directed toward anyone, but to be effective they must latch onto a similar vibration in the other person’s aura. If they are unable to do so, they can boomerang back on the sender. Thus, working according to the occult theory, one who directs evil toward another runs the risk of having it return.
The strength and clarity of the original thought determines the duration, strength and the distance of travel of its developed thought-form. It is said that thought-forms can have the capability to assume their own energy and appear to be intelligent and independent. Equally strong thought-forms can disperse them, or they may disintegrate when their purpose has been accomplished. Some may stay in existence for years, while others can become uncontrollable and turn on their senders.
Thought-forms, in magic, are also called “artificial elements,” which are created through ritual involving intense concentration, repetition, and visualization. (see Egrigor) They can be directed toward individuals to protect or heal, or to harm. Also, thought-forms can be created to perform low-level tasks and errands.
Other thought-forms can occur spontaneously, for example, “Group minds” that emerge whenever a group of people concentrate on the same thought, ideas, or goals, such as a team of employees or a crowd of demonstrators. To a certain extent the group-mind possesses the group, such is seen in psychic bonding and power that coalesces in crowds, and in the synergy of a close-knit working group. Usually when the group disbands the power of the group-mind dissipates too. A.G.H.
Source: 29, 616-617.