The symbol of the All-Seeing-Eye has always been part of Earth's creational mythologies and mysteries. As all of reality is a metaphor - there are many connected to the symbol of the eye.The third eye can see beyond the physical as it looks out through the chakrasystem when we meditate or look for answers from higher frequencies.
The 'third eye' can be activated to perceive higher dimensions.
'Third eye' development, imagination, and visualization are important ingredients in many methods to separate from the physical form. Intuition is also achieved through 'third eye' development. Knowledge and memory of the astral plane are not registered in full waking consciousness until the intuition becomes strong enough. Flashes of intuition come with increasing consistency as the 'third eye' as activated to a greater degree, through practice.
As the brain enters deeper states, our consciousness is less concerned with the physical state and our 'third eye' is active.
The pineal gland is occasionally associated with the sixth chakra (also called Ajna or the third eye chakra in yoga). It is believed by some to be a dormant organ that can be awakened to enable "telepathic" communication.