In both
traditional and
modern mythology, from the
Iliad to
Twin Peaks, an unbroken circle is a symbol of
unity,
purity, and
eternity. It is generally associated (in dualistic morality plays) with the
good guys.
It appears often in heraldry (most notably in the form of the Roman wreath - the circular bundle of sticks that give fascism its name).
In the legend of camelot, the table of King Arthur and his knights is an unbroken circle. The halo of angels and other judeo-christian blessed beings is traditionally circular. In Blade Runner, the unbroken circle of the human (or replicant) eye is a recurring motif. The list goes on and on...