Issac Asimov, an American author got the idea for his work during a subway ride in 1941. To get the idea for his story, he looked into a collection of Gilbert and Sullivan plays he had with him. He saw a picture of the Grenadier Guards in Iolanthe, which led him to soldiers, to military society, to feudalism, and to the breakup of the Roman Empire. When he reached John Campbell’s (a famous science-fiction writer) office, he told Campbell he had an idea for a new book which became popular as the foundation series.