Q. Whence originated the emblem of the all-seeing eye?
A. In most of the ancient languages of Asia, "eye" and "sun"
are expressed by the same word, and the ancient Egyptians
hieroglyphically represented their principal deity, the sun-god
Osiris, by the figure of an open eye, emblematic of the sun, by
whose light we are enabled to see, and which itself looks
down from the midst of heaven, and beholds all things. In like
manner masons have emblematically represented the omniscience
of the great Architect of the universe.
page 133
book Stellar Theology and Masonic Astronomy