But I forget!--the compelling interest of this day's journey is not literary. A short walk from Fuorigrotta brings me to a point where the road turns slightly upward to the right, leading me to the brow of a hill, over which I look into a wooded hollow--none other than the Lago d'Agnano, once a crater, then a volcanic lake. Oddly enough, it is not mentioned as a lake by any ancient writer. Pliny describes the Grotta del Cane, which we are about to visit, but says not a word of any lake. This fact, with some others, suggests that the water appeared in this old crater only in the Middle Ages; though it really does not matter much, for it is gone now. The bottom has been reft from the fishes and converted into fertile soil. The sloping heights which wall the basin have a waste and somewhat blasted aspect; but I was not granted time to muse on these appearances before a smiling but determined brigand, belonging to the class of guides, sauntered up with a small cur running at his heels and made me aware that I had reached the entrance of the Dog Grotto. I might have known it; for, in fact, through many centuries up to that recent year when it pleased the Italians to drain the lake, the life of the small dogs dwelling in this neighbourhood has been composed of progresses from grotto to lake and back again, first held up by the heels to be stifled by the poisonous gas, then soused head over ears in the lake with instructions to recover quickly because another carriage was coming down the hill. Thus lake and grotto were twin branches of one establishment, now dissolved. Perhaps the lake was the more important of the two, since it is easier to stifle a dog or man than to revive him; and on many occasions there would have been melancholy accidents had not the cooling waters been at hand. For instance it is related by M. de Villamont, who came this way when the seventeenth century was very young indeed, that M. de Tournon, a few years before, desiring to carry off a bit of the roof of the grotto, was unhappily overcome by the fumes as he stood chipping off the piece he fancied, and tumbled on the floor, as likely to perish as could be wished by the bitterest foe of those who spoil ancient monuments. His friends promptly dragged him out and tossed him into the lake. It is true the cure found so successful with dogs proved somewhat less so with M. de Tournon, for he died a few days later. Yet had the lake been dry, as it is to-day, he would have died in the cave, which would surely have been worse.