Celtic Shield Knots can be identified as any of the Celtic Knots with distinct corner areas. They usually look like 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 idea of the Celtic shield knot comes from civilizations older than the Celts. In ancient times, it was a universally known symbol to ward off danger and ward off evil spirits. The symbol always has a quadruple base, but within a larger unit.
The Mesopotamians used a similar four-cornered symbol to cast protective spells and to invoke the gods of the four corners of the Earth. The 4 cornered symbols represented the four creator gods. The sky god An was the greatest of these gods. Anki was the Sumerian word for universe. A sky meaning. Enlil was the next greatest god and could produce raging storms in an attack or help man when he was calm. He was known as the shepherd of the people and also as the god of the air. “lil” meant wind in the Sumerian language. The earth goddess was Nin-khursag (or Nintu). The fourth god was Enki, the god of water and patron of wisdom. The Sumerians believed that Heaven and Earth were united as a single mountain. Nammu, goddess of the primeval sea, gave birth to An (Heaven) and Ki (Earth). An and Ki gave birth to their son Enlil (god of the air). Enlil then took his mother, the Earth, from Heaven. In essence, these four gods represent heaven, fire, earth, and water. It is possible that the Celtic shield knots represent these same substances.
The ancient Norse, who eventually formed the Celts, had a similar shield symbol. His four-pointed symbol, which was also of protection, was related to the solar cross. The solar cross is one of the oldest spiritual symbols in the world. It is simply a cross with arms of the same size, inside a circle and touching the sides of the circle, which forms four open spaces. The Norse knew it as the cross of Odin, their chief god. The solar cross represents the movements of the sun as in the solstices (the four seasons). The Asatruar (Pagan Norse) people use the sun cross as their religious emblem.
Occultists using a system of ceremonial magic based on the Kabbalah (the mystical aspect of Judaism) invoke the four main archangels mentioned in Judaism (Michael, Gabriel, Raphael, and Uriel) as guardians. They are to protect the four quarters (as seen in a solar cross), or directions. Each has corresponding colors associated with magical properties. They also show spiritual activity in each season: spring is Raphael, summer is Uriel, fall is Michael, and winter is Gabriel. For these occultists, the symbol of the solar cross or shield knot represents this.
Christianity, in the Scandinavian area, eventually took the pagan symbol of the sun cross or shield knot and named it the cross of Saint Han (or cross of Saint John, after John the Baptist). It came to symbolize flowing water and the continuity of life, similar to the infinity symbol. Christianity is known for changing the meaning of many formerly pagan symbols as it spread. In Northern Europe, even today, the shield knot symbol is used to symbolize national heritage sites. In heraldry, the same knot symbol is known as a Bowen’s cross.
So we can say that the original celtic shield knot The symbol is indicative of the four seasons or earth, water, fire and sky (which help us, but have power over us). It can also mean the four gods, intertwined with the seasons, or archangels, who protect the people of the earth and bring us the elements or the seasons.