The Oracle of Delphi

The myth tells that the Pythia, the priestess who pronounced oracles in the name of the god Apollo in the sanctuary of Delphi (in Greece), did so in a state of mystical euphoria induced by the vapors that escaped from a crack in the rock.

In reality, the temple is located in a particularly active area from the seismic point of view and under it two faults have been identified, from which it is possible that gas was emitted.
The nature of the gas and its hallucinogenic properties, however, is still debated. Some speculate it was ethylene, some benzene or a mix of methane and carbon dioxide.