Some ancient cultures deified the moon as a goddess, and attributed to its phases three successive stages of femininity. The Maiden, for the waxing moon, represented new life, creativity and beauty. The Mother, or full moon, represented fertility and nurture. The Crone, or waning moon, represented wisdom, mortality and, um, bingo.
When these three get together for a drink, it'll be a blue moon before the barman dares ring his bell!