Eye of Ra
From Thelemapedia
Usage as a title
Avenger godforms of Ra were given the title 'Eye of Ra' and represented Ra's wrathful nature. The godforms were supposed to have come about by Ra glancing with his eye and creating them - this is why the Eyes of Ra were often referred to as Ra's children. The Egyptians presumably based this idea on the sun itself, and how too much sunshine and firey heat can be destructive.
The most famous incident of an Eye of Ra in typical, vengeful form is found in the myth of Sekhmet and Ra. Mankind had disobeyed and mocked Ra, who decided to create Sekhmet and send her to destroy man. Sekhmet proceeded to joyfully slaughter everyone she saw, until Ra pitied mankind. He could not stop Sekhmet, and so decided to trick her by pouring beer, coloured with red ochre, onto some fields. When Sekhmet came across the fields, she thought the beer was blood and drank until she was unable to kill. Now pacified, Ra declared that Sekhmet was now to be known as the peaceful Het-Hert.
This myth caused Het-Hert to be known as an Eye of Ra along with Sekhmet, Tefnut, Aset, Wadjet, and Nekhbet.
The Eyes of Ra were not only vengeful, but served as protectors too. Those who bore the title were often called upon to guard the innocent and vulnerable.
Usage as a symbol
Sometimes the Udjat, otherwise known as the Eye of Heru, was known as the Eye of Ra. When Udjat is a right eye, it is supposed to represent the sun and therefore Ra. This usage is quite uncommon.