Far back in the cave, where the blue shades are deepest, is a shelf of rock, the only place within the grotto at which one can land. It is usually occupied by a boy who pesters visitors by offering to dive in return for as many francs as he can extort. The sight of his body in the silvery water has excited various writers to high flights of eloquence, one of them indeed assuring us that here alone we can realise what we shall look like in heaven, when the grossness of our bodies has been purged away into the radiance of ethereal light. If this is so one should rejoice, though on more human grounds I regret the presence of the boy, whose avarice detracts from the charm of the grotto. The aspect of his body in the water is less wonderful than he believes. Moreover, the shelf which he has turned into a bathing board has a higher interest than any which it derives from him. For at this spot, and this only, is conclusive evidence that other eyes, in ages far distant from our own, have beheld this grotto, though, for reasons to be given presently, it is practically certain that those eyes saw a different sight. It is easy to discern a squared opening, like a door or window, in the rock above the ledge. Probably such visitors as notice it regard this as a modern contrivance to serve some purpose of the guides; but it is not so. It stands untouched since Kopisch saw it when he swam in half blinded by the smoke. When he, first of all men of our age, climbed up on the rock ledge and peered through the opening he felt confident that he had found the secret exit from the palace of Tiberius at Damecuta; and nothing has yet been discovered which disproves the possibility of this. The boatmen will have it that the passage goes to Anacapri. Mine was positive upon the subject, and though constrained to admit that his conclusion had not been proved, yet did not regard it as open to discussion. Tradition has a certain value where proof is not available; and as the passage is blocked at no great distance from the grotto, it may be long before the boatman's faith is shaken. Kopisch followed it as far as possible. He describes several corridors radiating in different directions through the hillside, forming a sort of labyrinth in which his party almost lost themselves, and in which they were finally checked by the presence of mephitic vapours.