The Triple Goddess

"The Triple Goddess is the subject of much of the writing of Robert Graves, and has been adopted by many neopagans (notably Wiccans) as one of their primary deities . 

The term triple goddess is infrequently used outside of Neopaganism to instead refer to historical goddess triads and single goddesses of three forms or aspects. In common Neopagan usage the three female figures are frequently described as the Maiden, the Mother, and the Crone, each of which symbolizes both a separate stage in the female life cycle and a phase of the moon, and often rules one of the realms of earth, underworld, and the heavens. These may or may not be perceived as aspects of a greater single divinity. 

The feminine part of Wicca's duotheistic theological system is sometimes portrayed as a Triple Goddess, her masculine counterpart being the Horned God.

Modern neo-pagan conceptions of the Triple Goddess have been heavily influenced by the prominent early and middle 20th century poet, novelist and mythographerRobert Graves who regarded the Triple Goddess as the continuing muse of all true poetry and who speculativley reconstructed her ancient worship, drawing on the scholarship of his time, in particular the Cambridge Ritualists.

More recently the prominent archaeologist Marija Gimbutas has argued for the ancient worship of a Triple Goddess in Europe, attracting much controversy, and her ideas also influence modern neo-paganism.

Many neopagan belief systems follow Graves in his use of the figure of the Triple Goddess, and it continues to be an influence on feminism, literature, Jungian psychologyand literary criticism."

Source and More information

http://en.wikipedia.org/wiki/Triple_Goddess_(Neopaganism)