Together with its two sequels ("The Imaginary" and "The Hazing") which form a 'Homo Sol Trilogy', the story is primarily set in a university environment. "Homo Sol" was the nineteenth story written by Asimov, the eighth to be published, and the second to appear in Astounding, which was then the world's leading science fiction magazine. In the Homo Sol stories, the Galactic Federation has developed psychology into a hard science, with quantitative equations and solutions for behavior. Consequently, master psychologists are important and highly regarded. The Solarians (meaning humans, also referred to as Homo Sol) have developed hyperspace travel and landed on a planet of Alpha Centauri, thus qualifying for acceptance into the Galactic Federation of intelligent humanoid species. Tan Porus, master psychologist at Arcturus University, is invited to join the delegation to be sent to administer the invitation, but sends one of his assistants. The delegation returns in despair; not only have the Solarians refused the invitation, but they exhibit irrational and war-like behavior that contravenes the sacrosanct psychological laws established over millennia by Federation psychologists.