The core of the Greater Mysteries occupied the events of the second night in Eleusis. In this case, on the night of the 21st of Boedromion, the entrance to the Telesterion was allowed only to the prospective epoptai. Epopteia was the highest degree of initiation for those who wanted to delve into the essence of the goddess's teaching. Mystai became eligible for epopteia one year after their initiation. Unfortunately, we know nothing for sure about the rituals of epopteia, and all the theories that have been proposed from time-to-time stumble upon the problematic nature of the ancient sources that obscure rather than enlighten the issue.