In ancient times, people from all over Europe traveled to Greece to have their questions about the future answered by the oracle of Delphi. Turns out she was just zooted from Earthly vapours in fault lines directly under the temple.
https://www.nationalgeographic.com/science/2001/08/greece-delphi-oracle-gas-vapors-science/
https://www.nationalgeographic.com/science/2001/08/greece-delphi-oracle-gas-vapors-science/