LUMEN. You are mistaken, my friend. The undulations of ether pass through obstacles that you would believe impenetrable. Clouds are formed of molecules between which rays of light frequently pass. In the contrary case, there are here and there vistas or gaps, across which one can only see obliquely. The case is very rare when nothing can be distinguished. Besides, light is not what it appears to be; it is a vibration of ether, and there are other ways of seeing than by means of the retina and the optic nerve. The vibrations of ether are perceptible to senses other than those you possess. Therefore, if this be your sole objection, it is, I must say, far from being an insurmountable one. QUÆRENS. You have a special faculty for resolving all doubts. Perhaps this is one of the gifts granted to spiritual beings. I have been obliged successively to admit, that you have been transported to Capella with a swiftness exceeding that of light; that you reached another world as a spirit; that your soul is liberated from the flesh; that your ultra-earthly perception is able to distinguish from that height all that passes here; that you can advance or recede in space according to your fancy; and lastly, that the clouds themselves are no obstacles to your clearly seeing the surface of our globe. It must be owned that these are grave difficulties indeed. LUMEN. You are very material, my old friend! Should you be very surprised if I undertook to prove to you that all these difficulties exist only in name, and that all the objections which oppose themselves to your conception of phenomena are the effects of ignorance? What should you think if I affirmed that no one has a single true idea of what takes place upon the Earth, and that man utterly fails to understand nature? QUÆRENS. In the name of all the indisputable truths of modern science, I should dare to think that you were trying to impose upon me. [Sidenote: The marvels of spectral analysis.] [Sidenote: Piercing nature of the soul's sight.]