http://www.bibliotecapleyades.net/ciencia/ciencia_thirdeye.htm

"The physiological site of this sixth Chakra, the Ajna, is located in the center of the forehead. It is symbolized by an eye - the so-called third eye, the inner eye, or the eye of the mind. When this eye is opened, a new and completely different dimension of reality is revealed to the practitioner of yoga. Western scholars when they first encountered this literature, took the third eye to be an appropriately poetic metaphor and nothing else."