Excerpt: ...shade! Every night,-do we really realise the full force of the inconvenience?-every night the sun commanded social life to desist and social life desisted. Humanity was actually to that extent the slave of nature! To think it never succeeded in, never even dreamed of, freeing itself from this slavery which weighed so heavily and unconsciously on its destinies, on the course of its progress thus straitened and confined! Ah! Let us once more bless our fortunate disaster! What excuses or explains the weakness of the first immigrants of the inner world is the fact that their life was necessarily rough and full of hardships, in spite of a notable improvement after their descent into the caverns. They had perpetually to enlarge them, to adjust them to the requirements of the two civilisations, ancient and modern. That was not the work of a single day. I am well aware how happily fortune favoured them; how they again and again had the good luck when driving their tunnels to discover natural grottoes of the utmost beauty, in which it was enough to illuminate with the usual methods of lighting (which was absolutely cost-free, as Miltiades had foreseen) in order to render them almost habitable: delightful squares, as it were, enshrined and sparsely disseminated throughout the labyrinth of our brilliantly lighted streets; mines of sparkling diamonds, lakes of quicksilver, mounds of golden ingots. I am well aware that they had at their disposition a sum of natural forces very superior to all that the preceding ages had been acquainted with. That is very easy to understand. In fact, if they lacked waterfalls, they replaced them very advantageously by the finest falls in temperature that physicists have ever dreamed of. The central heat of the globe could not, it is true, by itself alone be a mechanical force, any more than formerly a large mass of water falling by hypothesis to the greatest possible depth. It is in its passage from a higher to a...