THE EYE OF HORUS

In the hieroglyphs of Ancient Egypt we find mention about the Eye of Horus, also known as the Udjat, wadjet, or Oudjat, which is a symbol for spiritual awakening, protection, the power of royalty and good health. Horus is a god from Egyptian mythology, who defeated powers of darkness, established order, harmony and productivity. Horus was the offspring of Isis and Osiris. 
When Osiris became the king of Egypt he was a good and just king; he established the rule of the law (Maat), and with the help of the god Thoth, he taught a new religion to men and the arts of civilization, thus, Egypt became prosperous and had peace.
However, his brother Seth feeling jealous, plotted against him, and Osiris was murdered. Then Isis, his consort, with the help of Thoth, brought Osiris back to life, and soon after, Horus was born. 
Osiris' task on earth was then completed, and he transfigured himself into a star being, which is Orion constellation, and went to be a ruler of the Kingdom of the dead, the Duat. 
Isis by her turn, is identified with Sothis (Sirius), being the astral mother of the living king. Sirius, the brightest star in the sky and its constellation, Canis Major, immediately follows Orion in its rising.
Horus grew up to be a prince, and later revenged his father Osiris, and when fighting Seth, Horus lost his left eye. The god Thoth then helped Horus, restored his eye, which then became a symbol of protection for the living and the dead, and he was proclaimed the king of Egypt.

There is a theory that the eye of Horus could be a map of the brain.

When we compare the symbol of Udjat (eye of Horus) with the picture of the brain, we can see a similarity. 

The eye represents the thalamus, the eye brow is the corpus callosum, the tear duct and tear drop symbolize the pituitary and medulla oblongata. The long spiral arch that goes down the eye is the cerebellum, and the small point on the end is the pineal gland, or third eye.

The Egyptians had many amulets depicting the Udjat which accompanied them to the afterlife, which were decorated with semi-precious stones on bracelets, necklaces, and pendants.. It was intended to protect the soul from harm and bad luck during the journey.

THE NECTAR OF IMMORTAL LIFE

There is a potion that when ingested, is believed to grant eternal life; it's the elixir of life, or nectar of immortal life. This elixir of life is known by many different names through many cultures; names such as, ambrosia, amrita, liquid gold, soma, haoma, etc. What is exactly this potion or elixir of life?
In the sacred Indian text of the Rig Veda, written by the seer Rishi Kashyapa, there is an entire chapter devoted to a mysterious substance called soma, also called Soma Pavamana or Indu, which promises eternal life. Soma is a drink of living drops that come from the stalks of a legendary soma plant.

Here are a few verses of the Rig Veda;
"Where light is perpetual, in the world in which the sun is placed, in that immortal imperishable world place me, Pavamana; flow, Indu, for Indra. Where in the third heaven, in the third sphere, the sun wanders at will, where the regions are filled with light, there make me immortal; flow, Indu, for Indra. Where there is happiness, pleasures. joy and enjoyment, where the wishes of the wisher are obtained, there make me immortal; flow, Indu, for Indra."

Many believe that soma is a compound found in a rare Himalayan plant called knotweed vine, which might be the potent antioxidant resveratrol proven to slow down the aging process.
The yogis believe that soma can be self-generated in the pineal gland, thus, rejuvenating the body. But, there is a special way to obtain the soma, and it's only through deep meditation practiced for long periods of time, as well as through a special Yogic exercise called khechari mudra, combined with the meditation.
Therefore, you must first delve into meditation practice with a pure intent and perseverance. 

Khechari mudra:
The word khechari means to roll back your tongue and focus on the point between your eyebrows, either with closed or open eyes. The purpose of this mudra is to raise the kundalini and access the immortal elixir produced in the pineal gland. According to the Vedas, this elixir brings health, spiritual awakening and immortality.
To practice it, roll your tongue upward and backward, so the lower surface of your tongue comes into contact with your upper palate. Stretch the tip of your tongue backward as far as possible, without straining and keep the pressure at that point. At the same time, focus your attention on the third eye center, between your eyebrows, with your eyes open or closed. You can also do rhythmic breathing exercises when doing the khechari mudra.