Is the instrument of the third eye.
The cave in the center of the head is the pupil, where the focus comes through.
Its true function is the transfer of the higher consciousness which you call Soul, from one to the other, creating at-one-ment of consciousness between disciples who are operating within the same level of development.
AW 1624, 553
Disciples meditating in the ajna contact the light of Pure Reason, or the Wisdom aspect of the Second Ray... They contact the Plan or Will aspect of the First Ray via the head center. As they contact the Plan, the light of Pure Reason gives them understanding or comprehension of it and it then becomes their will or intent, their purpose for incarnation.
A vortex of etheric substance, located from three to six inches outside of the forehead, reflecting the focused intent of the incarnate consciousness. The created thought-form, through the process of visualization, is impressed upon those devas whose responsibility it is to bring it into outer manifestation.
Is located between the eyes from three to six inches outside of the forehead and extending into the forehead. This center is relatively quiescent until such time as the threefold personality becomes more or less integrated and can be consciously focused on the mental plane. At this time the center is activated and plays an important part in the alignment of Soul, mind and brain. It relates the three in awareness and aids in the creation of a magnetic field of mind so important to the growth of a student's understanding. This magnetic field of mind is used by the Soul and the disciple in service to the race. When the disciple nears the Third Initiation, an interplay of energy is set up between the head center and the ajna which compels the entire system to reorientation. The word symbol for its function is "Divine Love-Wisdom".
S&I 30, 32