Trinity Knot or Rings (Triquetra)

TRINITY KNOT OR RINGS (TRIQUETRA) - The symbol has been used by Christians as a sign of the Trinity (Father, Son and Holy Spirit), especially since the Celtic revival of the 19th century.  When modern designers began to display the triquetra as a stand-alone design, it recalled the three-leafed shamrock which was similarly offered as a Trinity symbol by Saint Patrick.  The triquetra has been used extensively on Christian sculpture, vestments, book arts and stained glass.  It has been used on the title page and binding of some editions of the New King James Version.

Triquetra (Latin tri- "three" and quetrus "cornered") originally meant "triangle" and was used to refer to various three-cornered shapes.  It has come to refer exclusively to a particular more complicated shape formed of three vesicae piscis (the leaf-like shape in between two equal diameter circles when both centers are on the circumference of the other circle), sometimes with an added circle in or around the three lobes.  Also known as a "trinity knot" when parallel doubled-lines are in the graph, the design is used as a religious symbol adapted from ancient Celtic images by Christianity. 

A very common representation of the symbol is with a circle that goes through the three interconnected loops of the triquetra.  The circle emphasizes the unity of the whole combination of three forces. It is also said to symbolize God's love around the Holy Trinity.