Plutarch De Defectu Oraculorum 44

[44] And yet the school of Aristotle ¹ would make it appear that exhalation is the author of all these changes that have taken place in the earth, and that things of this nature must of necessity follow with it in disappearing, changing their locality, and bursting forth once more in full vigour. Plainly the same sober opinion is to be held regarding the spirits that inspire prophecy; the power that they possess is not everlasting and ageless, but is subject to changes. For excessive rains most likely extinguish them, and they probably are dispersed by thunderbolts, and especially, when the earth is shaken beneath by an earthquake and suffers subsidence and ruinous confusion in its depths, the exhalations shift their site or find completely blind outlets, as in this place they say that there are still traces of that great earthquake which overthrew the city. And in Orchomenos they relate that a pestilence raged and many persons died of it, and the oracle of Teiresias become altogether obsolescent and even to this day remains idle and mute. And if a like fate has befallen those in Cilicia, as we have been told, there is nobody, Demetrius, who could give us more certain information than you.

[44] Aristotle and his followers affirm that all this proceeds from an exhalation within the earth, and when this fails or removes to another place, or revives and recovers itself again, the phenomena proceeding from them do so too. The same must we say of the prophetical exhalations which spring from the earth, that their virtue also is not immortal, but may wax old and decay; for it is not unlikely that great floods of rain and showers do extinguish them, and that the claps of thunder do dissipate them; or else (which I look upon to be the principal cause) they are sunk lower into the earth or utterly destroyed by the shock of earthquakes and the confusion that attends them, as here in this place there still remain the tragical monuments of that great earthquake that overthrew the city. And in the town of Orchomenus, they say, when the pestilence carried away such multitudes of people, the oracle of Tiresias of a sudden ceased, and remains mute to this day. And whether the like has not happened to the oracles in Cilicia, as we have heard it hath, no man can better inform us than you, Demetrius.