For the Celts, the cross symbolized the four directions—north, south, east, and west—and the four gods who inhabited them. It also represented the four seasons of the Celtic year. It also symbolized the crossing of two paths: that of the living and that of the dead.
These Celtic symbols are thought to represent the tree of life. The four elements—earth, air, water, and fire—united with the energy represented by the circle that unites them all.