If everything appears thus to tend to extinction and death, it is because we do not know the secret of the conservation of energy. An end such as I have indicated is really unthinkable. The terms of the problem contain their own condemnation. It is admitted that force and matter can be neither created nor destroyed, and have therefore existed and acted from all eternity. If therefore the final result of the radiation of suns into space is their extinction and consequently the extinction of life on their attendant planets, then since an eternity has already elapsed during which energy has tended to equilibrium, there ought to be not a single sun, star or planet in existence. Now relatively, not to an eternal duration but only to a period like a lightning flash compared with that, say a trillion years, the life of a human race, of a planet, or even of a sun, is very short. Geologists talk of 20 to 30 million years for the whole duration of the geological eras from the origin of life on earth; physicists talk of 100 million for the constitution of the terrestrial globe from the liquid to the solid state; astronomers also assign 100 million years to the age of the Sun, and even less to its future duration. Even if we doubled or trebled these numbers, even if we multiplied them by ten or even a hundred, we should not arrive at the millionth part of a trillion years! Thus without going back to a previous eternity, if the energy of suns had no other final result but extinction we should not exist now and nothing that is would be. The universe was not made of one piece at the origin of things. This origin does not in fact exist. We find in space suns of every age. There are old ones, there are new ones. Here are cradles, yonder are tombs. If the first creations formed by matter and energy had not been renewed, there would no longer be a universe. All primitive energy which had animated the suns would be used up. Besides, matter and energy are but one. Just as in passing through a forest we find oaks in decay, green trees, and new growths, thus also does the celestial traveller encounter in space worlds long dead, dying worlds, worlds in full activity, and budding stars. Everything dies, but everything lives again. Among the last worlds in full vitality which I visited on my voyage among distant universes there was one which appeared particularly remarkable on account of the high state of social progress. Although this world is the most distant of all those suspected to exist in the depths of space, yet the human race which dwells there is not very different from ours, physically. It is divided into two sexes, and the organic forms somewhat resemble those of our race. But the social state is distinctly superior to ours. A perpetual harmony reigns among all the members of this vast family. Simple and modest, each of these beings has no higher ambition than gradually to raise himself in the knowledge of things and in moral perfection.