The intervention in the Kievan succession crisis by Duke Boleslaus the Brave of Poland in 1015–1019 was an episode in the struggle between Svyatopolk Vladimirovich the Accursed and his brother, Yaroslav the Wise, for the rulership of Kiev and Kievan Rus'. It occurred when Boleslaus, Svyatopolk's father-in-law, intervened on the latter's behalf. The intervention was initially successful as Boleslaus defeated Yaroslav's armies and temporarily secured the throne for Svyatopolk. Svyatopolk, however, was unable to retain his position after Boleslaus withdrew from Kiev and was defeated by Yaroslav in the following year. Chronicles of the expedition include legendary accounts as well as factual history and have been subject to varied interpretations.
Stanisław Lem (1921–2006) was a Polish science fiction, philosophical and satirical writer, best known for his novel Solaris. His works explore philosophical themes; speculation on technology, the nature of intelligence, the impossibility of mutual communication and understanding, despair about human limitations and humankind's place in the universe. They are sometimes presented as fiction, but others are in the form of essays or philosophical books. His works have been translated into 41 languages and have sold over 27 million copies. In 1976, Theodore Sturgeon claimed that Lem was the most widely read science-fiction writer in the world.