Aetna is a mountain on the island of Sicily, from which fire erupts with sulfur, as Isidorus says in book 14 chapter 6. This mountain has, on the side which the Eurus or Affricus blows,  caves full of sulphur which extend all the way to the sea, caves which, when they receive waves into themselves, make wind, which, having been agitated, brings forth fire from the sulphur, and for this reason smoky fire from this mountain often contaminates the ground. This is what Isidore says.

And certain shapes are said to appear often on this mountain and the groaning of Aetna and mournful voices are often heard by the inhabitants of the land around the mountain: as a result of which it is believed by the majority of people, that there are places of punishment there in which souls are punished; nevertheless, I do not assert this. But blessed Gregorius appears to make a mention of this in his dialogue.

original latin