The Eleusinian Mysteries were initiation ceremonies held every year in ancient Greece.
They are the "most famous of the secret religious rites of ancient Greece."
It is thought that their basis was an old agrarian cult which probably goes back to the Mycenean period (c. 1600 - 1100 BC)
Since the Mysteries involved visions and conjuring of an afterlife, some scholars believe that the power and longevity of the Eleusinian Mysteries came from psychedelic agents."
Author : Dudley Wright