The Triple spiral or Triskele is a Celtic and pre-Celtic symbol found on a number of Irish Megalithic and Neolithic sites and later examples found in the Celtic Christian illuminated.
Its place in Celtic communities represents the three realms – Land, Sea and Sky .The Triskele came to be associated with the Triple Goddess (maiden, mother, crone) in pre-Christian times .Personally I think the full meaning is still lost to history, symbolists believe it is reflective of many areas. The Celts did believed that the most important things in life came in threes: birth, death, rebirth; body, mind, spirit; earth, water, sky; past, present, future; father, son, holy ghost; and the triskele is believed to represents these tripartite meanings.
Spirit Mind Body
Life Death Rebirth
Past Present Future
Mother Father Child
Power Intellect Love
Creation Preservation Destruction
Triskele can also be thought as to represent motions, as all three arms are position to make it appear as if it is moving, and movement or motion is believe to signify energies, in particular within this Celtic Symbol the motion of action, cycles and progress.
Modern day interpretations of meanings or representations
Connection, Journeying, Development
Balance, Progress, Direction, Initiation, Centering,