The Triad

(from DailyOm)
A woman's life is filled with stages, milestones ushering in wondrous experiential apexes like the coming of fertility, motherhood, and wisdom. Three aspects, maiden, mother, and crone, have traditionally represented the bounties and new beginnings represented by each stage. The maiden is the aspect of new beginnings, youth, playfulness, spontaneity, and learning. A woman in the prime of her life can be said to be living under the aspect of the mother, who personifies fertility, strength, and stability. She is the gentle nurturer as well as the fierce lioness. Lastly, and by far the most misunderstood and yet in many ways the most deserving of reverence, is the crone, who holds within her all of the wisdom of the journeys of womanhood within her.


(from Wikipedia)
Maiden

Among Pagans and Newagers "The Maiden" represents enchantment, inception, expansion, the promise of new beginnings, birth, youth and youthful enthusiasm.

Mother

The Mother represents ripeness, fertility, sexuality, nurturance, fulfillment, stability, power and life.

Crone

The Crone represents wisdom, repose, death, and endings. Like the moon which waxes once again after the new moon and like in the year, where spring always follows winter. The Crone is an end, but she is always followed by the Maiden once more. It is death and rebirth, representing the common pagan belief of reincarnation as well as the renewing cycles of the moon and of the year.

Triadic imagery

In The White Goddess, Graves said:

the New Moon is the white goddess of birth and growth;
the Full Moon, the red goddess of love and battle;
the Old Moon, the black goddess of death and divination.

This relates the three life-thresholds of birth, procreation and death with phases of the moon. It should be noted that this order is not consistent with that usually cited by some Neopagans and that the triadic structure is not dependent upon the division of the lunar month into three phases.