Celtic Shield Knot

Celtic shield knot is like any of the Celtic knots with for distinct corner areas. They usually resemble a square but sometimes they are a square shaped emblem within a circle. As in all Celtic knots there is no beginning or end. The Celtic shield knot idea comes from civilizations more ancient than the Celts. It was a universally used for warding off evil spirits and protection from danger. The symbol is always fourfold based, but within a greater unity.
Shield knots have appeared in cultures around the world and have taken a variety of different forms.
In modern Celtic reconstructionist groups, the shield knot is sometimes invoked as a ward to keep negative energy away. In some traditions, the corners of the knot are meant to represent the four elements of earth, air, fire and water.