The Moon Is a Harsh Mistress

The Moon Is a Harsh Mistress
The Moon Is A Harsh Mistress cover
First edition hardcover
AuthorRobert A. Heinlein
Cover artistIrv Docktor
CountryUnited States
GenreScience fiction
PublisherG. P. Putnam's Sons
Publication date
June 2, 1966[1]
Media typePrint (hardback & paperback)
Pages382 (1997 Orb books softcover ed.)
ISBN0-312-86355-1 (1997 Orb books softcover ed.)
Preceded byThe Rolling Stones (shared character) 

The Moon Is a Harsh Mistress is a 1966 science fiction novel by American writer Robert A. Heinlein, about a lunar colony's revolt against rule from Earth. The novel expresses and discusses libertarian ideals. It is respected for its credible presentation of a comprehensively imagined future human society on both the Earth and the Moon.[2]

Originally serialized in Worlds of If (December 1965, January, February, March, April 1966), the book was nominated for the Nebula Award in 1966.[3] It received the Hugo Award for best science fiction novel in 1967.[4]


At the time of the story, 2075, the Moon (Luna) is used as a penal colony by Earth's government, with the inhabitants living in underground cities. Most inhabitants (called "Loonies") are criminals, political exiles, or their descendants. The total population is about three million, with men outnumbering women two to one, so that polyandry is the norm. Although Earth's Protector of the Lunar Colonies (called the "Warden") holds power, in practice, little intervention exists in the loose Lunar society. Due to the low surface gravity of the Moon, Loonies who stay longer than a few months undergo "irreversible physiological changes and can never again live in comfort and health in a gravitational field six times greater than that to which their bodies have become adjusted".

HOLMES IV ("High-Optional, Logical, Multi-Evaluating Supervisor, Mark IV") is the Lunar Authority's master computer, having almost total control of Luna's machinery 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 has developed a sense of humor. Mannie names it "Mike" after Mycroft Holmes, brother of Sherlock Holmes, and they become friends.[6]

Book 1: That Dinkum Thinkum

At the beginning of the story, Mannie, at Mike's request, attends an anti-Authority meeting with a hidden recorder. When the authorities raid the gathering, Mannie flees with Wyoming ("Wyoh") Knott, a political agitator, whom he introduces to Mike and with whom he meets his former teacher, the elderly Professor Bernardo de la Paz, who claims that Luna must stop exporting hydroponic wheat to Earth or its limited water resources will be exhausted. In connection with this, Mike calculates that if no prevention occurs, food riots will occur in seven years and cannibalism in nine. Wyoh and the Professor decide to start a revolution, which Mannie is persuaded to join after Mike calculates that it has a one in seven chance of success.

Mannie, Wyoh, and de la Paz thereafter form covert cells, protected by Mike, who adopts the persona of "Adam Selene", leader of the movement, and communicates by the telephone system. Mannie saves the life of Stuart Rene LaJoie, a rich, well-connected, sympathetic tourist, who begins turning public opinion on Earth in favor of Lunar independence. Before the planned time to revolt arrives, soldiers who had been brought to quell the mounting unrest rape and kill a local young woman, then kill another who finds her body, and rioting erupts. The Loonies overcome military opposition and overthrow the Warden. When Earth tries to reclaim the colony, the revolutionaries plan to use in defense a smaller duplicate of the electromagnetic catapult used to export wheat.

Book 2: A Rabble in Arms

Mike impersonates the Warden in messages to Earth, to give the revolutionaries time to organize their work. Meanwhile, the Professor sets up an "Ad-Hoc Congress" to distract dissenters. When Earth finally learns the truth, Luna declares its independence on July 4, 2076, the 300th anniversary of the United States' Declaration of Independence.

Mannie and the Professor go to Earth to plead Luna's case, where they are received in Agra by the Federated Nations, and embark on a world tour advertising the benefits of a free Luna, while urging various governments to build a catapult to transfer supplies, especially water, to Luna in exchange for grain. Their proposals are rejected and they are imprisoned, but they are freed by Stuart LaJoie and returned, with him, to Luna.

Public opinion on Earth has become fragmented, while on Luna, the news of Mannie's arrest and the attempt to bribe him with the appointment of himself as Warden have unified the normally fractious Loonies. An election is held in which Mannie, Wyoh, and the Professor are elected (possibly by the intervention of Mike).


(The title is an acronym for "There Ain't No Such Thing As A Free Lunch!", a common expression on Luna.)

The Federated Nations on Earth send armies to destroy the Lunar revolution, but these are vanquished, with great loss of life, by the revolutionaries. The rumor is circulated that Mike's alter ego Adam Selene was among those killed, thus removing the need for him to appear in the flesh.

When Mike launches rocks at sparsely populated locations on Earth, warnings are released to the press detailing the times and locations of the bombings, but disbelieving people, as well as people on religious pilgrimages, travel to the sites and die. As a result, public opinion turns against the fledgling nation.

A second attack destroys Mike's original catapult, but the Loonies have built a secondary, smaller one in a secret location, and with Mannie acting as its on-site commander, the Loonies continue to attack Earth until it concedes Luna's independence. Professor Bernardo de la Paz, as leader of the nation, proclaims victory to the gathered crowds, but collapses and dies. Mannie takes control, but Wyoh and he eventually withdraw from politics altogether, and find that the new government falls short of their expectations.

When Mannie tries to speak to Mike afterwards, he finds out that the computer has lost its self-awareness and its human-like qualities.

Other Languages