"Take any work on astronomy of the last century, or the beginning of ours. You will no longer find in it, it goes without saying, our tiny planet placed in the center of the universe. But you will meet at every step the idea of a central luminary — the sun — which by its powerful attraction governs our planetary world. From this central body radiates a force guiding the course of the planets, and maintaining the harmony of the system. Issued from a central agglomeration, planets have, so to say, budded from it; they owe their birth to this agglomeration; they owe everything to the radiant star that represents it still: the rhythm of their movements, their orbits set at wisely regulated distances, the life that animates them and adorns their surfaces. And when any perturbation disturbs their course and makes them deviate from their orbits, the central body re-establishes order in the system; it assures and perpetuates its existence. This conception, however, is also disappearing as the other one did. After having fixed all their attention on the sun and the large planets, astronomers are beginning to study now the infinitely small ones that people the universe. And they discover that the interplanetary and interstellar spaces are peopled and crossed in all imaginable directions by little swarms of matter, invisible, infinitely small when taken separately, but all-powerful in their numbers."