It is believed that the Eye of Horus symbol, in fact, represents the left eye of the Hawk God Horus that he lost during his fight with Seth. Horus’s right eye symbolizes the Sun and his left eye – the Moon. The story of the “torn out” eye is probably an allusion to the lunar phases (this destructed “empty eye” is associated with the New Moon and its miraculous restoration – the “full eye” – with the Full Moon).
In addition to the Ankh symbol, the Eye of Horus is nowadays one of the most famous symbols of Ancient Egypt.