"If the square is bound up with man and his works, with architecture, harmonious structures, writing and so on, the circle is related to the divine. The circle has always represented and still represents eternity, with no beginning and no end. An ancient text says that God is a circle whose centre is everywhere and whose circumference is nowhere.
The circle is an essentially unstable, dynamic figure. From it arise all rotating things, and all vain efforts to produce perpetual motion."
~ from Design As Art by Bruno Munari