THE CONCENTRIC CIRCLES
The concentric circles around or inside the triangle represent the three fundamental tendencies of nature (gunas): sattva (the tendency of balance), rajas (the tendency of action), tamas (the tendency of inertia).
As far as yantras are concerned, the circles may also symbolize the three aspects of time (past, present and future), the three fundamental levels of manifestation, the three fundamental states of consciousness (the wakeful state, the dreamful state and the state of dreamless deep sleep).
THE EFFECTS ON HUMAN PHYSIOLOGY
Concentration is a basic human necessity. All the remarkable achievements in the area of knowledge are the creation of centered and focused minds.
In order to acquire this state you should practice some techniques and get used to remaining centered. The mind becomes agitated and restrictive when influenced by the sense organs.
Physiologists have discovered that the exterior signals received through each eye are transmitted to the brain by almost 1 million nervous fibres which are gathered at the level of the optic nerve.
There is a partial crossing of the optic nerves in the optic chiasm. Thus, the left cortex is related to the right half of the visual area and the right cortex is related to the left half.
That is why the symmetrical geometric figures seem to be the best stimuli for both hemispheres and for the cortex. They generate similar effects in both sides, thus creating a state of focus.
The cells of the ganglions of the retina and the lateral cells that gather information for the visual cortex have a circular symmetry.
They react very well to circular shapes, to a spot or a point because their receptive field is circular.
Mandalas and yantras correspond to the inner structure of the cells of the retina. Their shape is based on the intuitive knowledge of tantric clairvoyants about the nature of the mind and about the human need to recognize sacred symbols.
They are an answer to this universal human aspiration and by the means of the archetypal language they transform our psychic energy, thus spiritualizing our life.
MAGICAL DRAWINGS AND THE TWO CEREBRALS HEMISPHERES
Recent research has proved that Westerners mostly use the left hemisphere, while their right hemisphere is less developed. This has led to a decrease of their imaginative abilities and to a lessened belief in spiritual values.
It has also been noticed that spiritual intuition is awakened when both cerebral hemispheres are balanced in the human being.
Yantra, as a symbol, represents an energy associated to a certain state of consciousness. For example, the yantra of Kali is not only a symbolic representation of Kali but also a foreshadowing in the physical level of the energy that she manifests and impersonates.
Consequently, a yantra awakens through its symbolic character, the left cerebral hemisphere while its geometrical structure acts on the right hemisphere.