We must now essay an explanation of certain peculiar features which 1 are said to have occurred in the recent Campanian earthquake. A flock of six hundred sheep is asserted to have been killed in the district near Pompeii, and there is no reason to suppose that this happened to the sheep through fright. We have said that after great earthquakes it is usual for a pestilence to occur. And no wonder, since in the depths of earth many deadly poisons lurk. In fact, the very atmosphere there, 2 being stagnant through some fault in the earth or the sluggish movement and the everlasting darkness that prevails, is dangerous to breathe. Or being poisoned by the fumes of the internal fires, when it is released from its long inactivity, it taints and pollutes this pure clear air above, and brings new forms of disease to those who inhale the unwonted draught. You remember, too, that we found the water lurking in the secret depths to be useless and even pestilential, since activity never stirs it, and the free breath of heaven never ruffles it. Being therefore thick and covered beneath gross eternal darkness 3 it contains only elements that are pestilential and injurious to our bodies. So, too, the atmosphere, which mingles with it and lies amid these marshes, scatters far and wide its poison when it issues out, and kills those who breathe it. The flocks, which the pestilence is wont to attack, feel the poisonous effects more readily, because they are more greedy in feeding. They live for the most part in the open, and they drink a great deal of water, which is chiefly responsible for the pestilence. Sheep are of rather delicate constitution, and, as 4 they keep their heads close to the earth, I am not surprised at their being attacked by the infection; they receive the blasts of tainted air just as it issues from the ground. If it had issued in greater volume, it would have injured man too. But the abundant supply of pure air counteracted it before it could rise high enough to be breathed by any human being. XXVIII