Wasson, Hofmann and Ruck proposed in 1978 that ergot on the barley was the agent. Critics hold that ergot as it grows is severely toxic and that no ancient technique for separating a psychoactive fraction has been demonstrated, and that fasting, darkness and staging account for the reported experience without pharmacology. The oath of silence means no participant account survives to test either reading against.
What would resolve this Residue analysis of drinking vessels securely tied to the Eleusinian sanctuary and to the rite rather than to general sanctuary use, with independent replication.
OpenArchaeochemistry and classical archaeologyR. Gordon Wasson, Albert Hofmann and Carl A. P. Ruck, The Road to Eleusis: Unveiling the Secret of the Mysteries