years, that is to say, less than 5,000,000 years, in coming from thence. I have ascended a ray of light from the Earth to these remote regions, and if my spiritual sight had been more perfect, I should have been able to distinguish not only the retrogression of history for 10,000 years or 100,000 years, but even for 5,000,000 years. QUÆRENS. Can the mind, then, by its powers alone, cross in this way the immeasurable spaces of the heavens? LUMEN. Not by its own power alone, but by making use of the forces of nature. Attraction is one of these forces. It is transmitted with a velocity incomparably superior to that of light, and the most rigorously exact astronomical calculations are obliged to consider this transmission as almost instantaneous. I will add that if I have been able to perceive events at such distances, it is not by the apprehension of a physical sense that I know them, but by a process incomparably more subtle, which belongs to the psychic order. The movements of the ether, which constitute light, are not luminous by themselves, as you know. The eye is not necessary in order to perceive them. A soul vibrating under their influence perceives them as well, and often incomparably better than an organic optical apparatus. This being psychical optics. For example, attraction crosses instantaneously the 148,000,000 of kilometres that separate the Earth from the Sun, whilst light occupies 493 seconds in this passage. QUÆRENS. What length of time did your voyage to that remote universe occupy? LUMEN. Have I not told you that time does not exist outside the movements of the Earth? Whether I employed a year or an hour, it would have been exactly the same period in infinity. QUÆRENS. I have thought it over, and the physical difficulties seem to me enormous. Permit me now to submit to you a strange thought that has just come into my head. LUMEN. It is to hear your reflections that I give you this narrative. QUÆRENS. I want to ask you if the same inversion would take place with the hearing as well as the sight? If you can see an event backwards from its real occurrence, can you also hear a discourse backwards, beginning at the end? This is perhaps a daring question, and apparently ridiculous, but in paradoxes where can one stop? [Sidenote: Light and sound.]