I've always been fascinated with symbolism in sacred art and use the circle in most of my artwork as the symbol of God.
Fun History
The word CIRCLE derives from the Greek "kirkos" which means hoop or ring.
Did you know that the circle has been known since BEFORE the beginning of recorded history. Circles in nature, like the Moon & Sun would have been observed.
medival scholars believed that circles were intrinsically divine & perfect
1700 BCE- The Rhind Papyrus gives a method to find the area of a circular field. The result equals 256/81 (3.16049) as an apporoximate value of π
In Plato's Seventh Letter he includes a detailed definition & explaination of the circle. He explains the perfect circle, and how it is different from any drawing, words, definition or explanation.
Halo's in religious art are perfect "eternal" rings surrounding a holy or sacred figure.
