Triquetra - Three-pointed symbol seen hanging from the cat's collar and on the Book of Shadows on the occult drama CHARMED/WB/1998+. The Triquetra or "Trinity Knot". was used in pre-Christian times by the Celts to represent the triple goddess (Maiden, Mother and Crone). Early Celtic Christians used the symbol to represent the trinity of God the Father, Jesus Christ, and the Holy Spirit. The Triquetra is also used as a feminine symbol of protection from evil,  or as a representation of the triple Goddess. (the pedal-like protrusions representing the "yoni" or female vulva or womb). The circle represents eternity. The power of the Triquetra symbol is used by the Halliwell sister (Piper, Prue, and Phoebe)  three young women who discovered that they were witches known as "The Charmed Ones." The symbol is first called a Triquetra in episode "Witch Trial" (2.01) when Prue suggests the Triquetra represents the three of them working as one.  See also BOOKS: "Book of Shadows"  

TRIVIA NOTE: The symbol of the Triquetra appeared on the cover of the Led Zepplin's fourth rock & roll album entitled Stairway to Heaven.  The four images represented the musicians Page, Jones, Bonhan and Plant. The first and fourth design were created by Page and Plant while the second image (The Triquetra) are based on Celtic Runes. The Triquetra image stands for confidence and Bonham's images  of three intersecting circles represents the trilogy: man, wife and child.

Led Zeppelin Album Symbols