The Pythia at Delphi

The popular image of her chewing laurel leaves over volcanic fumes is later embroidery. Ancient sources describe a rising vapour, and it was only in 2001 that geologists actually confirmed ethylene gas escaping from a fault beneath the temple — nearly two thousand years after the last oracle was given.

Plutarch, De defectu oraculorum (c. 100 CE); de Boer, Hale and Chanton, Geology (2001), on the ethylene seep