The rite's mythic charter is the Homeric Hymn to Demeter, composed around the 7th century BCE. Hades seizes Persephone while she gathers flowers, and Demeter, goddess of grain, searches for her in grief so consuming that she withholds the harvest from the earth. The gods broker a compromise, Persephone eats pomegranate seeds binding her to the underworld for part of each year, and Demeter, appeased, teaches her rites to the people of Eleusis before restoring the world's fertility. Where standard Homeric religion offered the dead only a grey, diminished existence, Eleusinian initiation promised something better, and this contrast is likely what drew so many prominent Greeks and Romans to seek it, including Cicero, who called it among the finest gifts Athens had given the world, and the emperor Marcus Aurelius.
Scholars have long debated whether the kykeon drunk before the climactic rite carried a psychoactive effect; Wasson, Hofmann and Ruck proposed in 1978 that an ergot derived compound in the barley could explain the vivid effects ancient sources describe, a theory still discussed but never proven. The Mysteries endured for roughly two millennia, spreading Eleusinian style initiation cults across the Greco Roman world, until the Christian emperor Theodosius I's edicts against pagan sacrifice in 391 and 392 CE stripped the rite of legal standing, and Alaric's Goths sacked the sanctuary itself in 396 CE, ending organised practice at Eleusis for good.