QUÆRENS. Two years have fled, Lumen, since the day when you granted me that mysterious interview. During this period, unconsciously for the inhabitants of eternal space, but most consciously for us dwellers upon the Earth, I have often raised my thoughts to the great problems in which you have initiated me, and to the horizons developed before my mind's eye. Doubtless, also, since your departure from the Earth you have made, through your observations and studies, great advance upon a field of research more and more vast. Doubtless, also, you have numberless marvels to declare to me, now that my intelligence is better prepared to receive them. If I am worthy, and if I can comprehend them, give me an account, Lumen, of the celestial voyages which have transported your spirit into the higher spheres; of the unknown truths which they have revealed to you; of the grandeurs which they have opened out to you, and of the principles they have taught you in reference to that mysterious subject, viz., the destiny of man, and other beings. LUMEN. I have prepared your mind, my dear old friend, to receive marvellous impressions, such as no earthly spectacle ever has, or could produce. It is, nevertheless, necessary that you should keep your understanding free from all earthly prejudice. That which I am going to unfold will astonish you, but receive it from the first with attention as an undeniable truth, and not as a romance. This is the first condition that I demand from my earnest pupil. When you comprehend--and you will comprehend, if you bring to the task a mathematical mind and an unprejudiced spirit--you will see that all the facts which constitute our ultra-terrestrial existence are not only possible, but also real, and moreover, are in perfect harmony with our intellectual faculties as already manifested upon the earth. QUÆRENS. Be assured, Lumen, that I bring to you an open mind, cleared from all prejudice, and I am eagerly expecting to hear revelations such as the human ear has never before heard. [Sidenote: Space and Light.] LUMEN. The events which will form the subject of this recital have not only the Earth and its neighbouring stars for their subject, but they will extend over immense fields of sidereal astronomy, and make us acquainted with their marvels. Their explanation will be solved, as was that of former difficulties, by the study of _light_, a magic bridge thrown from one star to another, from the Earth to the Sun, from the Earth to the stars--of _light_, the universal movement which fills space, sustains worlds in their orbits, and constitutes the eternal life of nature. Take care, then, to keep ever in mind, the fact of the _successive transmission of light in space_. [Sidenote: Velocity of Light.]