The shield knot is an ancient and nearly universal symbol. The shield knot has been used for thousands of years by a variety of cultures for protection and warding. While the common design is most often associated with the Celts and ancient Norse, the most basic form is much older.

The fourfold version at right is Mesopotamian in origin and is associated with protective spells invoking the gods of the four corners of the earth. Later, the four-corners emblem was used in the Kabbalah as a symbol of the Shema, the prayer/spell to invoke the four Archangels; it is the origin of the “Qabbalistic Cross” ritual still used in magic today. This knot is sometimes referred to as the “Earth Square” or St. Hans cross, named for the biblical John the Baptist. The Norse and Celtic versions of the knot are used for the same purposes of protection but are related to the fourfold solar cross.