Transitions between life and death are presented by the move from one world to another. In the Greek Classical tradition, Hades is both the god of the underworld, and the place.
Hades is presented as an otherworld, darker than the bright home of the Gods (Mount Olympus) but a physical place that may be reached by crossing the river Styx. However, that transition means joining the dead. Many Greek myths (including those of Persephone/Demeter, Achilles, Hercules, and Orpheus) include stories where heroes bravely enter the underworld to connect with the dead. Persephone (the girl, Kore) is abducted to the underworld by the god Hades, living there for half of the year, and returning to bring light and warmth to the earth. Her mother, Demeter, is the corn goddess.
Greek funeral statuary often shows a girl (Persephone) holding a pomegranate, a woman (Demeter) her mother, and Hecate (the wise woman or hag) associated with crossroads and transitions – and three ways.
Trimorphic Form – The Triple Goddess
Hecate is often depicted in trimorphic form (as three aspects of woman) or with 3 heads: serpent, dog, and horse. Cerberus (the hound who guards the gates of Hades) is also presented as a three-headed beast. The triple aspect of goddesses, of crossroads suggests multiple paths, identities, and archetypal figures of whom we know little but which appear to be central to mystery cults relating to birth and death, the seasons and sacrifice for fertility. The triple forms of Persephone/Demeter/Hecate are: the girl, corn-mother, and crone.