Ancient civilizations and cultures believed in the power of the amulet to protect them from hidden malevolent forces that they thought were everywhere. These forces could take the form of disease, floods, earthquakes or almost any natural disaster, illness or tangible foe. To combat and protect themselves against these forces, ancient people wore amulets or charms around their neck, ankles, wrists or anywhere else on their bodies. The amulet could be an object – natural or man-made – believed to be endowed with special powers to heal or protect or bring good fortune.
The ancient Egyptians believed the “Eye of Horus” to be a potent amulet. Its symbolism served as a powerful protection against harm and evil both on earth and in the afterlife.
Frequently, explanation to many ancient peoples’ beliefs can be found in their mythology. In the mythology of ancient Egypt, Horus was the falcon-headed sun and sky god who was associated with vitality, health, and regeneration. He was the son of Osiris (god of life, the Underworld, & fertility) and Isis (goddess of magic, life, and love). Osiris and Isis ruled over Egypt but Set, the god of night and darkness, evil, and death, was jealous over the throne and killed Osiris. Horus made war on Set to avenge his father's death. During the fight, Horus lost his left eye but Thoth, the god of magic used his powers to restore Horus’ eye. The Eye of Horus became a potent symbol of the power of the god of light, and therefore a popular amulet for protection, good fortune, and healing. The eye also symbolized the ability to see with clarity and truthfulness. Representation of the Eye of Horus consisted of an image of either the left or right eye and eyebrow, along with a stylized beard.

The imagery of the Eye of Horus was later adopted by the Greeks, Romans, and Arabs and in time evolved into the prescription sign “Rx" – so it has been claimed. As proof, “Horus believers” say that each segment of the eye represented a fraction, thus enabling the ancient apothecaries to write a prescription using the different segments to specify how much of each ingredient the medicine should contain. Contrarians to this theory state “R” stands for recipe, the Latin word for “take.” The “x” was originally a dash through the extended tail of the preceding “R”, which was supposedly a symbol of the Roman god, Jupiter, under whose protection all medicines were placed. Jupiter (Greek Zeus) was the supreme god of the Roman pantheon of deities and god of light and sky.
Personally, I think it most likely that the prescription “Rx” sign originated from the Eye of Horus imagery of the ancient Egyptians. The Egyptian civilization is much older than the Roman and the Romans adopted many medical practices from the Egyptians. Both schools of thought however, trace the “Rx” iconography to the invocation of powerful gods to augment the power of medicines prescribed.
The symbol has survived to our time and brings home the fact that medicine has its roots in magic.
 

Rachel Hajar, M.D.