“Let us see what some of that knowledge is. You know, to begin with, that one world is inhabited. Then if you should find other bodies as large as the earth and bearing any resemblance to it, there would be no improbability in the thought that they or some of them were filled with life. The improbability is certainly taken away by the knowledge that one such body, the earth, is inhabited. “You start, then, without prejudice, on a voyage of discovery, aided by your telescope and your reasoning faculties. “First you find, within distances that you can easily measure, a small group of dark bodies, which you have called planets, all apparently governed by a common law, in obedience to which they are circling around a large body of quite different character, which gives them light and heat. Of these dark bodies, which shine in the sky only by reflected light, the earth is one, and, you are surprised to find, not the most important one, judging from all you can discover. Some of the others are much larger and are attended by more satellites. In fact, the earth is indistinguishable in this little group. While it is not the largest, neither is it the smallest. It is not the farthest from the sun nor the nearest to it. It is merely one among the number. And how much alike the members of this family are. Your telescopes do not point out any material differences, although each has its individual characteristics. Let us enumerate some of the many points of resemblance. They all turn on themselves as well as revolve around the sun. All see the night follow the day, and in most of them there must occur the regular succession of seasons. To each one the sun is the source of light and heat, many of them have moons, and all can see the stars. Nor does the resemblance stop here. For you have discovered that one has an atmosphere, another is surrounded with clouds, while on the surface of our own globe you see the polar snows increase in winter and melt away in summer. Is it not probable that if you could get nearer to these globes you would find still closer resemblances? And if they are like the earth in so many ways, is it at all unlikely that they may, at some period of their existence, be the abode of intelligent life? For what other purpose were they made, Doctor?” “They make very pretty objects for us to look at,” replied my companion. “Yes, those that can be seen,” said Thorwald; “but is that all? Were those great worlds, some of them hundreds of times larger than your own globe, created merely to add a little variety to your sky, and to give you the pleasant task of watching their movements under the pretty title of morning and evening star?” “Speaking from the knowledge I had when I left the earth,” the doctor answered, “I can say I never heard that they were put to any other use. No one ever came down to us from any of them to tell us they were inhabited.”