The Eye of Horus

an ancient Egyptian symbol of protection.

Horus was the ancient Egyptian sky god who was usually depicted as a falcon. His right eye was associated with the sun Ra. The sun was an eye of Horus (the other eye, semi-blind, was the moon), "when he opens his eyes, he fills the universe with light, and when he closes them, darkness is created".

In one myth, when Set and Horus were fighting for the throne after Osiris's death, Set gouged out Horus' left eye. The eye was restored by either Hathor or Thoth.

In the Ancient Egyptian measurement system, the Eye Of Horus defined Old Kingdom number one (1) = 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64, by throwing away 1/64 for any rational number. Eye of Horus numbers created six-term rounded-off numbers.