"Grant that your explanation is correct," I said, "yet I can not understand how a quiet lake of water can give rise to a convulsion such as the eruption of a volcano." "Not only is this possible," he responded, "but water usually causes the exhibition of phenomena known as volcanic action. The Island of Ischia, in which the volcanic crater Epomeo is situated, is connected by a tortuous crevice with the peaceful pool by which we now stand, and at periods, separated by great intervals of time, the lake is partly emptied by a simple natural process, and a part of its water is expelled above the earth's surface in the form of super-heated steam, which escapes through that distant crater." "But I see no evidence of heat or even motion of any kind." "Not here," he replied; "in this place there is none. The energy is developed thousands of miles away, but since the phenomena of volcanic action are to be partially explained to you at a future day, I will leave that matter for the present. We shall cross this lake." I observed as we walked along its edge that the shore of the lake was precipitous in places, again formed a gradually descending beach, and the dead silence of the space about us, in connection with the death-like stillness of that rigid mass of water and its surroundings, became increasingly impressive and awe-inspiring. Never before had I seen such a perfectly quiet glass-like surface. Not a vibration or undulation appeared in any direction. The solidity of steel was exemplified in its steady, apparently inflexible contour, and yet the pure element was so transparent that the bottom of the pool was as clearly defined as the top of the cavern above me. The lights and shades of the familiar lakes of Western New York were wanting here, and it suddenly came to my mind that there were surface reflections, but no shadows, and musing on this extraordinary fact, I stood motionless on a jutting cliff absorbed in meditation, abstractedly gazing down into that transparent depth. Without sun or moon, without apparent source of light, and yet perfectly illuminated, the lofty caverns seemed cut by that aqueous plane into two sections, one above and one below a transparent, rigid surface line. The dividing line, or horizontal plane, appeared as much a surface of air as a surface of water, and the material above that plane seemed no more nor less a gas, or liquid, than that beneath it. If two limpid, transparent liquids, immiscible, but of different gravities, be poured into the same vessel, the line of demarkation will be as a brilliant mirror, such as I now beheld parting and yet uniting the surfaces of air and water. Lost in contemplation, I unconsciously asked the mental question: "Where are the shadows?" My guide replied: