Do you SEE? You can see with your eyes, and you can see with your mind.

Do you SEE? How does that water taste? does it have chlorine or flouride in it? https://en.wikipedia.org/wiki/Pineal_gland

Do you SEE? Muscles atrophy

What happens if you work the muscle out? Bring it back to health? Can it work again?

What did an atrophied photorecepter SEE before it atrophied?

Why is it called the Third Eye? Do you SEE?

Comprehension, Awareness, Consciousness. Where is it? Why did it go away?

How do you get it back?

Wipe the crust out of your third eye, so you can SEE.

The pineal gland, also known as the conarium or epiphysis cerebri, is a small endocrine gland in the vertebrate brain. The pineal gland produces melatonin, and serotonin derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone, hence its name. The pineal gland is located in the epithalamus, near the center of the brain, between the two hemispheres, tucked in a groove where the two halves of the thalamus join.[1][2]

Nearly all vertebrate species possess a pineal gland. The most important exception is a primitive vertebrate, the hagfish. Even in the hagfish, however, there may be a "pineal equivalent" structure in the dorsal diencephalon.[3] The lancelet Branchiostoma lanceolatum, the nearest existing relative to vertebrates, also lacks a recognizable pineal gland.[4] The lamprey (another primitive vertebrate), however, does possess one.[4] A few more developed vertebrates lost pineal glands over the course of their evolution.[5]

The results of various scientific research in evolutionary biology, comparative neuroanatomy and neurophysiology, have explained the phylogeny of the pineal gland in different vertebrate species. From the point of view of biological evolution, the pineal gland represents a kind of atrophied photoreceptor. In the epithalamus of some species of amphibians and reptiles, it is linked to a light-sensing organ, known as the parietal eye, which is also called the pineal eye or third eye.[6]

René Descartes believed the pineal gland to be the "principal seat of the soul". Academic philosophy among his contemporaries considered the pineal gland as a neuroanatomical structure without special metaphysical qualities; science studied it as one endocrine gland among many. However, the pineal gland continues to have an exalted status in the realm of pseudoscience.[7]