Every world has a beginning and an end. A world may be destroyed by collision with a larger world.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“fire is composed of small spherical atoms, and so is the soul. Atoms, by collision, produce vortices, which generate bodies and ultimately worlds.* There are many worlds, some growing, some decaying; some may have no sun or moon, some several. Every world has a beginning and an end. A world may be destroyed by collision with a larger world. This cosmology may be summarized in Shelley’s words: Worlds on worlds are rolling ever From creation to decay, Like the bubbles on a river Sparkling, bursting, borne away. Life developed out of the primeval slime.” source