The secrets were fiercely guarded, and severe penalties were prescribed for anyone who divulged them or who, like Alcibiades, were thought to have profaned them. Initiates were required to undergo initiation rites which may have included transvestism and centred on secret objects (perhaps phalluses) and passwords being revealed.
The aim was to give devotees a glimpse of the “other side”, so that they could return to their lives blessed in the knowledge that when their turn came to die they could ensure the survival of their soul in the Underworld.
Excavations have uncovered tombs containing passwords and instructions written on thin gold sheets as an aide-memoire for deceased devotees. The principal Greek Mystery Cults were those of Demeter, goddess of agriculture, and of Dionysus (also known as Bacchus), god of wine, ecstasy – and of theatre.
See other: Which Greek Legends Were Really True?