consider her to be eternal and imperishable. But of the powers which are about her it is to be expected that some should fail here, and others come into being there, and that there should be shiftings from place to place, and cross-currents, and that such cycles should often revolve within her if we take time as a whole; and the phenomena point to such an inference. For in the case of lakes and rivers, and still more frequently in that of hot springs, there have been failure and entire disappearance in some places, in others a retreat so to call it, and an absorption; [Sidenote: 434] then they reappear at intervals of time in the same places, or bubble up in their neighbourhood. Again, we hear of mines where the ore has been exhausted and then renewed, as in the silver mines of Attica, and the copper lodes of Euboea, out of which the chilled sword-blades used to be manufactured, as Aeschylus[191] has said _Th’ Euboean blade, self-tempered, in his hand._ Then there is the rock at Carystus where it is only lately that the yield of delicate thread-like filaments of mineral has ceased. I think some of you will remember having seen towels, and nets, and caps made of these, which were non-inflammable. [Sidenote: B] Any which were soiled by use were placed in a flame out of which they came bright and clear. Now there has been an entire disappearance of these, and scarcely a few fibres or thin filaments run in streaks about the mines. XLIV. ‘Yet Aristotle[192] holds that exhalation is the operative cause within the earth of all these things, that is, of the natural effects which necessarily fail, shift place, and break out concomitantly. The same view must be taken of prophetic currents; the power which they have is not perennial nor ageless, it is liable to changes. Probably they are extinguished by excessive storms of rain, and dispersed by thunderbolts [Sidenote: C] falling upon them; above all, when the earth is shaken, and subsidence or conglomeration takes place in her depths, the exhalations are shifted or wholly lost to view; thus the effects of the great earthquake which actually overturned the town are said to be permanent here. In Orchomenus they say that there was a pestilence in which many men perished, and that the oracle of Teiresias then wholly failed, and remains to this day idle and voiceless. If the like happened also to those in Cilicia, as we hear it did, there is no one, Demetrius, who could tell us about it more clearly than you.’