Far from having any title to immortality Vesuvius is among the youngest and most mutable of mountains. The present cone is, as I said, the creation of the last eighteen centuries, piled up by successive eruptions to something more than the height of Somma, which once, as its name implies, towered far above it. Even though the antiquity of the mountain be reckoned by the age of Somma, or of some earlier cone, on the ruins of which Somma may have reared itself, it is as nothing when set beside the great wall of mountains which sweeps round the plain and ends in the great crags of St. Angelo and the cliffs of Capri. Those hills may be termed "eternal" by as true a warrant as any on the earth. But long after they were shaped and fashioned the sea flowed over the Campagna Felice and the site of Naples. Vesuvius was a volcanic vent-hole underneath the water, like many another which now seethes and hisses deep down in the blue bay, forming lava reefs about which the best fish always cluster. Then came the upheaval of the sea floor, and Vesuvius stood on dry land, no longer a sea-drenched reef or islet, but a hill of ashes and of lava piled over a crack in the earth's crust, which belched forth fiery torrents for unnumbered years, and sank at last to rest after an outburst which, if one may judge by the hugeness of the crater it scooped out, must have been terrible almost beyond conception. Yet it was completely forgotten! How many centuries of rest must it not have needed to erase from the minds of men all memory of a cataclysm so tremendous! In the days when doom was drawing near to the cities of the Campagna, an old tradition was current that fire had once been seen coming out of the summit of Vesuvius. Doubtless many people looking up at the green mountain pastures shrugged their shoulders at the tale. Yet Strabo, the geographer, remarked that the rocks upon the surface of the mountain looked as if they had been subjected to fire. It is difficult for us to detach the idea of terror from Vesuvius, and to contemplate it with thoughts at all resembling those which the dwellers in the buried cities bestowed upon it. There has, however, been one period when the summit of the mountain presented an aspect probably not far unlike that which a Pompeiian would have seen, had curiosity led him to the top after visiting his vineyards or his pastures on the lower slopes. That time was in the years immediately preceding the eruption of 1631. Vesuvius had been almost at rest for near five centuries, and there were many who believed its fires to be extinct.