The Eye of Horus, also known as wadjet, wedjat or udjat, is an ancient Egyptian symbol of protection, royal power, and good health. The Eye of Horus is similar to the Eye of Ra, which belongs to a different god, Ra, but represents many of the same concepts. Funerary amulets were often made in the shape of the Eye of Horus. The symbol "was intended to protect the pharaoh in the afterlife" and to ward off evil. Ancient Egyptian and Middle-Eastern sailors would frequently paint the symbol on the bows of their vessels to ensure safe sea travel.
Horus
was the ancient Egyptian sky god who was usually depicted as a falcon, most likely a lanner or peregrine falcon. His right eye was associated with the sun god, Ra. The eye symbol represents the marking around the eye of the falcon, including the "teardrop" marking sometimes found below the eye. The mirror image, or left eye, sometimes represented the moon and the god Djehuti. It was believed by the Greeks and Romans that an evil heart could get to the eye. The thought to be powerful effects of eyes and optics created the myth that the energy-producing power of the eye had the ability to cast evil spells with just a glance. Because the ancients believed the evil eye could be counteracted with a 'good eye', myths about Horus arose. In one myth, when Set and Horus were fighting for the throne after Osiris's death, Set gouged out Horus's left eye. The majority of the eye was restored by either Hathor or Thoth. When Horus's eye was recovered, he offered it to his father, Osiris, in hopes of restoring his life. Hence, the eye of Horus was often used to symbolise sacrifice, healing, restoration, and protection.
There are seven different hieroglyphs used to represent the eye, most commonly "ir.t" in Egyptian, which also has the meaning "to make or do" or "one who does". In Egyptian myth the eye was not the passive organ of sight but more an agent of action, protection or wrath. The Eye of Horus was represented as a hieroglyph, designated D10 in Gardiner's sign list. It is represented in the Unicode character block for Egyptian hieroglyphs as U+13080.
Mathematics
In Ancient Egypt, most fractions were written as the sum of two or more unit fractions, with scribes possessing tables of answers. Thus instead of, one would write +. Different parts of the Eye of Horus were thought to be used by the ancient Egyptians to represent one divided by the first six powers of two: The Rhind Mathematical Papyrus contains tables of "Horus Eye Fractions". Studies from the 1970s to this day in Egyptian mathematics have clearly shown this theory was fallacious and Jim Ritter definitely showed it to be false in 2003. The evolution of the symbols used in mathematics, although similar to the different parts of the Eye of Horus, is now known to be distinct.
