The Eleusinian Mysteries are one of the most compelling and fascinating cultural artifacts of ancient Greece. Their origins are found in the Homeric Hymn to Demeter. In this Homeric, Demeter, goddess of the earth, travels to Eleusis to find her daughter Persephone, who was abducted by Hades, the god of the underworld. While Demeter is gone, the earth languishes and the gods become worried. Zeus intervenes; however, Hades has Persephone eat a pomegranate, which connects her to Hades for a third of every year. Also in her journey, Demeter befriends the royal family of Eleusis and agrees to bring up the queen's son. She plans to make the boy eternally young, but when the boy's mother finds out she reveals herself as the goddess and demands a temple be built for her. Overall, the themes of the Mysteries revolve around honoring Demeter and hoping for life after death.
When Eleusis was incorporated into Athens, that city took charge of the festival to honor Demeter, although it retained its local flavor. A holy truce was called for fifty-five days for all of the Greek city-states.
The Mysteries start with the Initiates' march from Athens to Eleusis. There, at the Hall of Initiation (the Telesterion), the rites were performed. It is unknown precisely what happened in these rites, although they did begin with purification rites, called the Lesser Mysteries and held at Agrai outside of Athens in February-March. The Greater Mysteries were held in September-October and included bathing in the sea, fasting for three days, and another, more complicated and ambiguous rite. Sacred objects, called the Hiera, were used, stored in a temple near the Acropolis in Athens before the celebration and carried along with the procession. Shouts of "Iacchus", identified as Dionysus, the avatar of excitement and energy, were shouted; some other versions of the myths said Iacchus was the son of Demeter or Persephone. The rituals within the Telesterion were secret, only revealed to the Initiates. It is said that the priestesses revealed the vision of the holy night and/or revealed the seeds in a stalk of grain. The fasting was also broken when the Initiates drank a potion that symbolized Demeter's refusal to imbibe red wine. On the last day (scholars estimate that there were nine) the procession returned to Athens, carrying to sacred objects.
During the Hellenistic age, the Mysteries grew even more popular. They were run by the state and aristocratic families officiated. Mystery cults were well known, and it required very little (to be without blood guilt and to understand Greek) to be an Initiate. Thousands of people participated. Men, women, and slaves were allowed to participate.
The Mysteries ended when the Roman Emperor Theodosius closed the sanctuary in 392 CE. Christianity later came to the region, and these "pagan" rites could no longer be celebrated.