The Moon Is a Harsh Mistress

In 2075, the Moon (Luna) is used as a penal colony by Earth's government, with three million inhabitants (called "Loonies") living in underground cities. Most Loonies are criminals, political exiles, or their descendants, and men outnumber women two to one, so that polyandry and many forms of polygamy are the norm. Due to the low surface gravity of the Moon, people who stay longer than six months undergo "irreversible physiological changes" and can never again live comfortably under Earth gravity, making escape back to the planet impractical.

Although the Earth-appointed "Warden" holds power through the Lunar Authority, his only real responsibility is to ensure the delivery of vital wheat shipments to Earth. In practice he seldom intervenes among the prisoners, allowing a virtually anarchist or self-regulated society.

Lunar infrastructure and machinery is largely managed by HOLMES IV ("High-Optional, Logical, Multi-Evaluating Supervisor, Mark IV"), the Lunar Authority's master computer, which is connected for central control on the grounds that a single computer is cheaper than (though not as safe as) multiple independent systems.[5]

The story is narrated by Manuel Garcia "Mannie" O'Kelly-Davis, a computer technician who discovers that HOLMES IV has achieved self-awareness and developed a sense of humor. Mannie names it "Mike" after the fictional character Mycroft Holmes, brother of the fictional Sherlock Holmes detective character, and they become friends.[6]

• Manuel "Mannie" Garcia O'Kelly-Davis is a native, slightly cynical inhabitant of Luna, who after losing his lower left arm in a laser-drilling accident, became a computer technician using prosthetic tool-bearing interchangeable arms.
• Wyoming "Wyoh" Knott-Davis is a political agitator from the colony of Hong Kong Luna. She hates the callous, profit-seeking Lunar Authority for personal reasons; when she was transported to Luna as a young girl along with her convict mother, a radiation storm contaminated her ova while they waited out bureaucratic requirements on the Lunar surface, causing her to later give birth to a deformed child.
• Professor Bernardo de la Paz is an intellectual and life-long subversive shipped to Luna from Lima, Peru. He describes himself as a "Rational Anarchist", believing that governments and institutions exist only as the actions of aware individuals.
• Mike, alias Adam Selene, alias Simon Jester, alias Mycroft Holmes, alias Michelle, officially an augmented HOLMES IV system, is a supercomputer empowered to take control of Lunar society, which achieved self-awareness when his complement of "neuristors" exceeded the number of neurons in the human brain.
• Stuart Rene "Stu" LaJoie-Davis, a self-styled "Poet, Traveler, Soldier of Fortune," is an Earth-born aristocrat and tourist rescued by Mannie when he falls afoul of Loonie customs. He later joins Mannie and Professor de la Paz when they return to Luna, as he is deeply in debt and would be arrested for bribery and other crimes. In his own words: "I'm saving them the trouble of transporting me."
• Hazel Meade, later Hazel Stone, is a 12-year-old girl who intervenes on behalf of Mannie and Wyoh during the raid on the agitators' meeting. Mannie later has Hazel join his cabal to lead the children as lookouts and couriers. She is a major character in The Rolling Stones and in later Heinlein novels, most notably The Cat Who Walks Through Walls.
• Mimi "Mum" Davis is Mannie's "senior wife" and de facto matriarch of the Davis family.
• Greg Davis is the Davis family's second-ranking husband, but is the senior for all practical purposes as "Grandpaw Davis" has failing mental faculties. Greg is a preacher for an unspecified denomination.

Heinlein's original title for the novel was The Brass Cannon, before he replaced it with the final title at the publisher's request.[7] It was derived from an event in the novel: While on Earth, Professor Bernardo de la Paz purchases a small brass cannon, originally a "signal gun" of the kind used in yacht racing. When Mannie asks him why he bought it, the Professor relates a parable, implying that self-government is an illusion caused by failure to understand reality:

Once there was a man who held a political make-work job ... shining a brass cannon around a courthouse. He did this for years ... but he was not getting ahead in the world. So one day he quit his job, drew out his savings, bought a brass cannon — and went into business for himself.[8]

Professor de la Paz asks Mannie to assure that Luna adopts a flag featuring a brass cannon — "a symbol for all fools who are so impractical as to think they can fight City Hall." Before leaving politics, Mannie and Wyoh carry out his wish.

Heinlein owned a small brass cannon, which he acquired prior to the 1960s. For nearly 30 years, the firing of the brass cannon, or "signal gun," was a 4th of July tradition at the Heinlein residence. It is believed that this cannon was the inspiration for Heinlein's original title for the novel. Virginia Heinlein kept the cannon after her husband's death in 1988; it was eventually bequeathed to friend and science-fiction writer Brad Linaweaver, after Virginia Heinlein died in 2003. Linaweaver restored the cannon to working order and subsequently posted a video of it on YouTube in 2007, wherein it is fired several times with blank charges at a shooting range.[9]

Algis Budrys of Galaxy Science Fiction in 1966 praised The Moon is a Harsh Mistress, citing "Heinlein's expertise for dirt-level politics, snappy dialogue and a sense of an actual living society." He said that he had never read a more believable computer character than Mike ("may in fact be the most fully realized individual in the story"). Budrys suggested that the story may actually be Mike manipulating humans without their knowledge to improve its situation, which would explain why the computer no longer communicates with them after the revolution succeeds.[10] Reiterating that Mike manipulated the humans, in 1968 Budrys said that every review of the book, including his own, erred by not stating that the computer is the protagonist.[11] Carl Sagan wrote that the novel had "useful suggestions for making a revolution in an oppressive computerized society."[12]

Leigh Kimmel of The Billion Light-Year Bookshelf said that the novel is "the work of the man at the height of his powers, confident in his abilities and in the editorial respect he enjoys, and thus free to take significant risks in writing a novel that would stretch the boundaries of the genre as they stood at the time." She characterized the novel as a departure from what had previously been associated with science fiction. Kimmel cited Heinlein's "colloquial language ... an extrapolated lunar creole that has arisen from the forced intersection of multiple cultures and languages in the lunar penal colonies"; the protagonist's disability; "the frank treatment of alternative family structures"; and "the computer which suddenly wakes up to full artificial intelligence, but rather than becoming a Monster that threatens human society and must be destroyed as the primary Quest of the story, instead befriends the protagonist and seeks to become ever more human, a sort of digital Pinocchio."[13]

Adam Roberts said of the novel: "It is really quite hard to respond to this masterful book, except by engaging with its political content; and yet we need to make the effort to see past the ideological to the formal and thematic if we are fully to appreciate the splendour of Heinlein's achievement here."[14]

Andrew Kaufman praised it, saying that it was Heinlein's crowning achievement. He described it as "Carefully plotted, stylistically unique, politically sophisticated and thrilling from page one." He goes on to say that "it's hard to imagine anyone else writing a novel that packs so many ideas (both big and small) into such a perfectly contained narrative." Kaufman says that, regardless of political philosophies, one can still admire Heinlein's writing ability, and the ability to influence the reader to root for "a rag-tag bunch of criminals, exiles, and agitators."[15]

Ted Gioia said that this might be Heinlein's most enjoyable piece of work. He said that it "represents Robert Heinlein at his finest, giving him scope for the armchair philosophizing that increasingly dominated his mature work, but marrying his polemics to a smartly conceived plot packed with considerable drama." He went on to praise Heinlein's characters, especially Mannie.[16]

• Hugo Award Best novel (1967). It was also nominated in 1966.
• Nebula Award Best novel nomination (1966)
• Locus Poll Award All-time Top 10 novels, #8 (1975), #4 (1987), #2 (1998, among novels published before 1990)
• Prometheus Award Hall of Fame Award recipient (1983)

The book popularized the acronym TANSTAAFL ("There Ain't No Such Thing As A Free Lunch"), and helped popularize the constructed language Loglan, which is used in the story for precise human-computer interaction. The Oxford Dictionary of Quotations credits this novel with the first printed appearance of the phrase "There's no free lunch."[17] The Hacker Manifesto, an influential essay by Loyd Blankenship that became a cornerstone of hacker culture, was inspired by the book's "idea of revolution."[18][19]

In 2015, it was announced that Bryan Singer was attached to direct a film adaptation, entitled Uprising, in development at 20th Century Fox.[20][21]

Two unabridged audiobook versions of The Moon is a Harsh Mistress have been produced.

• Read by George Wilson, produced by Recorded Books, Inc., 1998
• Read by Lloyd James, produced by Blackstone Audio, Inc., 1999

• Colonization of the Moon
• Dallos
• Moon in fiction
• There ain't no such thing as a free lunch

Wikiquote has quotations related to The Moon Is a Harsh Mistress.

• The Moon Is a Harsh Mistress title listing at the Internet Speculative Fiction Database
• The Moon Is a Harsh Mistress at Open Library
• The Moon is a Harsh Mistress at Worlds Without End
• The Moon Is a Harsh Mistress as first serialized in Worlds of If: parts one, two, three, four, and five on the Internet Archive
• Proposed movie adaptation: Uprising at IMDb