The significance of the pineal gland has been the subject of investigation for centuries, with its first documentation tracing back to a Greek doctor and philosopher known as Galen.
Galen’s colleagues believed the pineal regulated the flow of ‘psychic pneuma,’ or an ethereal substance referred to as ‘the first instrument of the soul.’ But Galen refuted this, instead, thinking the pineal was simply a gland that regulated blood flow.
A resurgence of supernatural characteristics associated with the pineal returned when René Descartes took interest in it. He asserted it was ‘the principal seat of the soul,’ and believed it to be the source of all thought. Descartes was essentially credited with reflex theory or the involuntary system of actions carried out in the body’s function.
He thought of this in the sense that the mind could be separated from the body, with the ability to take over the animal instincts, making its entrance through the pineal gland. Descartes believed the pineal was unique because it did not have a matching pair, like most other sensory organs.
“It must necessarily be the case that the impressions which enter by the two eyes or by the two ears, and so on, unite with each other in some part of the body before being considered by the soul. Now it is impossible to find any such place in the whole head except this gland; moreover, it is situated in the most suitable possible place for this purpose, in the middle of all the concavities.” – Réne Descartes
Shiva and other Hindu deities are often depicted with a literal third eye on their forehead. This eye represents an awakening, or enlightenment, as the ability to see into higher realms of existence and consciousness. Many interpret this third eye as the pineal gland.
Shiva’s dreaded hair wrapped in snakes looks strikingly similar to a pinecone, the namesake of the gland itself. Snakes in Hinduism are thought to be auspicious, most notably seen in imagery surrounding Kundalini Yoga.
The body’s chakras are often depicted in Kundalini by a winged staff encircled by two snakes, or a Caduceus as it is known in Greek mythology. The snakes meet at the Ajna chakra, where the pineal and pituitary glands are located. This chakra is known as the source of consciousness, with Ajna translating to command or guidance.
The ancient Egyptian civilization is well-known for many innovations that led to the development of modern systems and utilities that are used daily in the present world.
Among these innovations are discoveries in human anatomy and medicine that have led to surgical techniques and instruments still commonly used today. The Egyptians documented many of their findings by combining mythology and mysticism with facts.
Ancient Egyptians mastered the integration of anatomical knowledge and mythological stories into artistic symbols and figures. Artistically, the Eye is comprised of six different parts. Mythologically, each part is considered to be an individual symbol.
Anatomically, each part corresponds with the center of a particular human sensorium. For many years, the Eye of Horus was considered as a symbol of prosperity and protection by the ancient Egyptians, and its legacy continued into modern Egypt as well.
However, with a closer look at its artistic design and understanding the epic story behind its creation, the Eye’s current perception as a singular mythologic symbol will be transformed into a powerful example of the ancient Egyptians’ detailed understanding of human anatomy and physiology.
The Eye of Horus mythology begins with the story of Osiris. This story is the most recognized mythology in ancient Egypt. It illustrates the eternal fight between the virtuous, the sinful, and the punishment.
Osiris was the oldest son of the God of the Earth, Geb, and the Goddess of the Sky, Nut, and was known as the God of the Underworld but, more appropriately, as the God of Transition, Resurrection, and Regeneration.
Osiris had three siblings: Isis, Set, and Nephthys. Osiris married his sister, Isis, as was the timely Royal custom, and had a son named Horus. The myth started when Set, Osiris’ brother, murdered Osiris to claim the throne, which caused disorder and chaos in ancient Egypt.
Set’s brutality did not stop at killing Osiris, and he proceeded to cut Osiris’ body into 14 parts that were distributed across ancient Egypt.
According to the ancient Egyptian traditions, in order for a royal’s spirit to cross to the underworld, the body needed to be appropriately embalmed and buried in the royal tombs. This proper burial allowed the body to pass through the underworld gates and be judged according to their deeds.
Isis traveled with Horus in search of Osiris’s body parts. Isis also recruited the help of her sister, Nephthys, and Nephthys’ son, Anubis. Anubis was the son of Nephthys and Osiris, and it is said that Nephthys wickedly assumed the shape of Isis to seduce Osiris and conceive Anubis.
Isis, Nephthys, Anubis, and Horus were able to find 13 parts of Osiris. The spirit of Osiris was then able to pass to Amenti, the underworld, and rule the dead. When Horus killed Set in the large battle near Edfu, he proclaimed his kingdom, restoring the order to Egypt.
The ancient Egyptians used this legendary fight as a metaphor of the battle between good and evil, order and chaos. Afterward, Horus was idolized by the ancient Egyptians in the form of the Eye of Horus, which was considered as a symbol of prosperity and protection.
Ancient Egyptians were pioneers in art and medicine. This is exemplified in the artistic measurements of the Eye of Horus. The Eye of Horus was divided into six different parts called the Heqat fractions, in which each part was considered a symbol itself.
The Heqat is among the oldest Egyptian measuring systems in which the numerical values are perceived as a consequential pattern. Gay Robins and Charles Shute discussed this concept in their explanation of the ancient Egyptian mathematical measures of “The Rhind Mathematical Papyrus”, which is considered to be the oldest ancient mathematical script.
In the Rhind Mathematical Papyrus, the Heqat was described as a unit of volume, which is used for measurements of goods, such as grain and flour, and it was approximated as 4.8 liters, just over one gallon.
The Eye of Horus fragments were organized together to form the whole Eye, similar to the myth, and these fragments were given a series of numerical values with a numerator of one and dominators to the powers of two: 1/2, 1/4, 1/8, 1/16, 1/32, and 1/64. Some historians suggested that each part of the eye represents one of the six senses: smell, sight, thought, hearing, taste, and touch.
The 1/2 accounts for the sense of smell, the 1/4 represents sight, the 1/8 represents thought, the 1/16 represents hearing, the 1/32 represents taste, and the 1/64 represents touch. Surprisingly, if we superimposed these suggested parts over the mid-sagittal image of the human brain, each component corresponds to portions of human neuroanatomical features.
The Eye of Horus has been used for many metaphors over the years, i.e., “Eye of the Mind, Third Eye, Eye of the Truth or Insight, the Eye of God Inside the Human Mind.”
The ancient Egyptians, because of their beliefs in the Eye of Horus’ mystic powers, gave all of these names to the Eye of Horus.
To show the significance of the Eye of Horus in human neuroanatomy, we go beyond the visual world and explore the hidden mysteries of the human senses, starting with the sense of smell.
On the Eye of Horus, the smell is represented by the triangular shaped object on the right side of the Eye’s pupil, illustrated by the yellow triangle.
On a closer look, this triangular-shaped object was designed in a way to resemble the side view of the human nose as a symbol of smell and was given the 1/2 Heqat fraction. The 1/2 Heqat fraction is also in the identical location and shape of the olfactory trigone.
The human perceives vision when the light hits the retina inside the globe, sending neuronal electrical impulses through the optic pathways to the interthalamic adhesion (massa intermedia) where some of the thalamic fibers that carry the vision, along with other sensations, move towards the midline and then curve laterally to the same thalamus.
The impulses are sent from the thalamus to the optic radiation tracts and then to the visual cortex in the occipital lobes. On the Eye of Horus, the pupil of the Eye represents the sight or vision sensation and was given the 1/4 Heqat fraction.
The 1/4 Heqat fraction is also in the identical location and shape of the massa intermedia (interthalamic adhesion).
One of the metaphoric names of the Eye of Horus is the Eye of the Mind, which was named after its reputation as the symbol of wisdom or thought.
Wisdom is represented by the eyebrow of the Eye and given the 1/8 Heqat fraction. The eyebrow is often associated with thinking; for example, we move our eyebrows to express various emotions.
From the anatomical perspective, it resembles the corpus callosum. The corpus callosum is the largest collection of the white matter fibers within the brain and facilitates the rapid transmission of neuronal impulses between both hemispheres.
On the Eye of Horus, the eyebrow represents wisdom and was given the 1/8 Heqat fraction. The 1/8 Heqat fraction exactly resembles the location and shape of the corpus callosum.
On the Eye of Horus, hearing is represented by the triangular-shaped object and the lateral commissure (canthus) on the left side of the Eye’s pupil. The 1/16 Heqat fraction is aligned to the same location.
The taste sensation is carried to the thalamus, then to the primary gustatory area of the cerebral cortex for interpretation.
On the Eye of Horus, taste is represented by the curved tail and was given the 1/32 Heqat fraction. The 1/32 Heqat fraction of the Eye resembles the taste pathway in the human brain. We think that ancient Egyptians used this fraction as a part of their mystic arts.
Touch sensation is carried by the somatosensory pathway, which carries numerous sensations from the body, i.e., light touch, pain, pressure, temperature, joint and muscle position sense (proprioception).
These sensations are divided into three groups, and each group is carried by a different pathway in the spinal cord with a different target in the brain cortex. The first group includes touch, pressure, and vibration perception and allows us to define the shapes and textures of the objects without sight.
These senses are carried by the posterior column-medial lemniscus pathway of the spinal cord. The second group includes pain and temperature senses that are carried by the lateral spinothalamic tract.
The third group includes proprioception, which allows us to sense the relative position of body parts and the strength needed for movement. On the Eye of Horus, the touch sensation is represented by the straight object coming down from the right side of the Eye, and was given the 1/64 Heqat fraction. The 1/64 Heqat fraction of the Eye resembles the somatosensory pathway.
Although we recognize the liabilities of overinterpreting a symbolic masterpiece like the Eye of Horus, we propose that the anatomical metaphors in the Eye of Horus are not by coincidence and merit discussion.
The ancient Egyptians were leaders in medicine and anatomy. This can be found in documented papyrus, as well as the walls of many temples and tombs.
In the creation of Eye of Horus, ancient Egyptians combined their artistic abilities and knowledge of anatomy with their deep belief in mythology.
More importantly, we argue that there is a clear influence of their interpretation of human senses on the size and shape of the Eye. This is an amazing feat considering the unavailability of radiographic and computational technology in that era.
The significance of our theory of the Eye of Horus is not to be used as an anatomical gold standard but rather to acknowledge and appreciate the genius and foresight of an ancient civilization in decoding the intricate functions of the human central nervous system.