The third eye is a concept from Eastern mysticism that refers both to the sixth chakra (ajna chakra), and to the inward-looking awareness — insight — that is needed for spiritual growth.
In the chakra system, the third eye is the second-highest energy centre. It is situated inside the head, behind and slightly above the eyes. The yoga approach is to trigger the awakening of the kundalini energy from the base of the spine, and it is said that when it reaches the third eye, a higher level of consciousness and insight is achieved.
There is also some thought that the third eye has a physical basis in the pineal gland. This small pine-cone-shaped endocrine gland is situated almost at the centre of the brain, between the two hemispheres, and has been found to regulate seasonal and sleep/wake cycles. Some say that it is the seat of clairvoyance in the body.
The metaphorical meaning of the third eye is that our two physical eyes look out at the world outside us, while the third eye observes what is within us. In meditation, we become aware of the passing-by of our thoughts and feelings, while bringing the attention gently to the spaces between them. This in-sight can help us to build awareness and understanding of our own minds, and help us integrate ourselves into oneness.
As our insight grows, we gradually peel back the layers in the onion of self-understanding. By becoming an impartial observer, or witness, to all that is within us, we become unattached to our thoughts and feelings. We are told that eventually, it is inevitable that we will peel back the last layer of the onion, and realize that even the observer — our “self” — does not really exist.