The basic principle of The Left Hand of Darkness is one that started in Ursula K. Le Guin's first novel in 1966 and runs through several of her early works: that of the interplanetary expansion started by the first race of humanity on the planet Hain and expanded across the universe, forming the League of All Worlds, eventually expanding to the eighty-three-world collective called the Ekumen. This novel takes place in the year 4870 and concerns an envoy, Genly Ai, who is on a planet called Winter ("Gethen" in the language of its own people) to convince the citizens to join the Ekumen. Winter is, as its name indicates, a planet that is always cold, and its citizens are neither female nor male: they only have gender identities or sexual urges once a month. These conditions have affected the ways that civilizations on Winter have developed, with the most obvious effect being that there has never been a war on the planet. There are, however, arcane rules of politics and diplomacy that the envoy must learn in order to survive. His fortune changes quickly, according to what political faction is in power at the time in the country he is residing in: in one country, for instance, the Prime Minister arranges an audience with the king for him, but the next day the Prime Minister is exiled for treason; in another he has trouble determining which factions among the thirty-three Heads of Districts support him and which want to use him to gain political power. The struggle of Genly Ai as he tries to understand the ways of these people and survive on this hostile planet gives Le Guin the chance to explore what life would be like without the dualities, such as summer and winter or male and female, that form our way of thinking: the book's title comes from a Gethen poem, which begins, "Light is the left hand of darkness ..." This book received the most prestigious awards given to science fiction writing: a Hugo Award in 1969 and a Nebula Award in 1970.