Like all symbols, those found in Celtic art, literature, jewelry, architecture, and decorative objects contain deeper spiritual and magical significance. The four most popular symbols used today--knots, serpents (or dragons), the cross, and spirals--can be found on artifacts dating back to the eighth century B.C.E.
Although exquisitely beautiful as design motifs, Celtic knots are not purely decorative. Knotwork symbolizes the continuing cycle of life, death, and rebirth––and the many twists and turns along the way. Celtic knots also represent the path to the ancestors, one's inner self, and divine inspiration--much as the labyrinth does.
The cross is a poignant symbol to both Pagan and Christian Celts, but its meaning in the two traditions is somewhat different. To Christians, the cross represents the crucifixion and resurrection of Jesus Christ. To Pagan Celts, the cross depicts the junction or union of two polar energies. The horizontal portion signifies the earth; the vertical symbolizes the heavens. In both viewpoints, however, the the cross signifies eternal life, a bridge between the physical and spiritual realms.
Serpents and dragons depict wisdom. In Celtic spirituality, as in many other traditions, the snake represents the life force as well as hidden (or occult) knowledge. Dragons are seen as keepers of secrets, as well as the gatekeepers to other worlds. The spiral shape depicts the path inward and outward, as well as the flow of life energy.