The circle is probably one of the most ancient symbols, and it often symbolized the sun. One of the most universal meanings is though infinity, since circles have no beginning and no end. This idea is strengthened in celtic circles by the weaved knots which endlessly enrichen their design. Celts also believed circles were magical doorways to access different levels of existence, such as the worlds of spirits and of gods.

A curiosity: celtic circles are often used as frames to enclose other designs, and are easily found coupled with triskells.