“Two analogies, one mechanical and one chemical, may help you, if not to understand the process at least to see how it is possible. Suppose a string of immense length so thin as to be quite invisible; and suppose it to be knitted and woven and re-woven until it be formed into a piece of cloth, compact but very small. Suppose the process of knitting or weaving to be performed very quickly, and then suppose the web so formed to be as rapidly unravelled again. In that case the piece of cloth would appear and disappear just as you have seen our bodies do. “Or suppose two vast masses of oxygen and hydrogen in the proportions in which they exist together as water. Suppose them to be brought together and subjected to the chemical process which is needed in order to make them combine: what happens? A small quantity of water suddenly appears. Reverse the process and it disappears. “By means roughly analogous to these we are able to assume terrestrial bodies and to pass into the ether again. But while our bodies are in terrestrial form they are subject to the same laws as yours; we need food and sleep, and we are subject to the various accidents and conditions of humanity.” Here he paused for a moment and Jack spoke. “But you are not subject to death as we are. Any cause that would kill us only resolves your material bodies into their ethereal form.” “That is the case,” he said; “but the difference is not such as you suppose. All the material of your bodies is ultimately resolved into ethereal matter, but not all of it is essential to your being, and that which is essential is resolved by a much speedier process. “But to speak of ourselves: while we remain in our own world we have instruments of sensation fitted to our condition and analogous to yours, just as hearing is analogous to seeing. But I cannot explain to you any more exactly our means of sensation, just as you could not explain sight to a man born blind. “But our sensations are throughout strictly analogous to yours and pass into yours when we assume terrestrial bodies.” Here he paused again, and I asked, “Can you see our worlds from yours?” “No,” he replied. “The ether as far as we know pervades the universe and passes freely through worlds like yours, and we, while dwelling in the ether, have no more cognisance of your world than you of ours.