The three-cord plait
	Knot #1
	Knot #2
	The four-cord plait
	Knot #3
	Knot #4
	Knot #5
	Knot #6
	Knot #7
	Knot #8

Origin

Prior to the Christian influence on the Celts (about A.D. 450), the only known Celtic artwork consisted of geometrical patterns such as spirals, key patterns, and step patterns. It has been suggested that the Celts' religion prevented them from depicting the works of the creator, namely animals, plants, and humans. That is why their artwork is restricted to geometrical patterns.

Many of these patterns have similar or identical counterparts in early Christian manuscripts and artwork. There can be no doubt that the Christian Celtic artwork was strongly influenced by pagan Celtic sources. However, it is only in the artwork of the Christian era that we see knotwork. Besides knotwork, the Christian Celts also added human, plant, and animal forms to their decorations.

Plaitwork, which is a pattern of interwoven (but unknotted) cords, is the earliest form of knotwork. For examples of plaits, see the eight basic knotwork forms.

Plaitwork is not unique to the Celts; examples are found in many cultures. By breaking the plait's cords and reattaching them, knotwork patterns can be derived. The first examples of this practice came in the early 700's A.D. in Italy. This is about the time that the Book of Lindisfarne, the earliest illuminated manuscript featuring knotwork patterns, appeared.

Meaning

J. Romilly Allen has identified eight basic knots from which most Celtic knotwork patterns were derived. These knots appeared in repeating patterns that were used to fill borders and empty spaces in illuminated manuscripts, sculptures, and jewelry. The knots did not, generally, appear as isolated elements.

Therefore, it's my opinion that the Celts did not use knots as specific symbols. They did not have different knots to represent specific ideas or concepts. Knots were just nifty ways to fill a space. The symbolism of connectedness and continuity seem apparent from simply looking at knotwork patterns. This may have been an intended effect, but I've uncovered no evidence to suggest that knotwork patterns mean anything more than that.