Giant spiders and tiny people, bloody battles of ants, desperate fights of microbes, journeys inside the human body, and unimaginable universes contained in atoms—the penetration into the micro-world has long been a cherished dream of science fiction writers. The classic American literature book by M. Twain, “Three Thousand Years Among the Microbes,” continues, in the “Polaris” series, the publication of forgotten and rare works united by the common theme of “adventures in the micro-world.” The book includes the fantastic story “Three Thousand Years Among the Microbes” and fragments of the unfinished novel “The Great Darkness.”