Heinlein was the first science-fiction writer to break into mainstream general magazines such as The Saturday Evening Post in the late 1940s with unvarnished science fiction, and he was among the first authors of bestselling novel-length science fiction in the 1960s. For many years Heinlein, Isaac Asimov, and Arthur C. Clarke were known as the Big Three of science fiction. He won seven Hugo Awards, three of them retrospectively, as well as the first Grand Master Award given by the Science Fiction Writers of America for lifetime achievement.

The major themes of Heinlein's work were social: radical individualism, libertarianism, solipsism, religion, the relationship between physical and emotional love, and speculation about unorthodox family relationships. His iconoclastic approach to these themes has led to wildly divergent perceptions of his works. His 1959 novel Starship Troopers was excoriated by some as being fascist. His 1961 novel Stranger in a Strange Land, on the other hand, put him in the unexpected role of pied piper to the sexual revolution and counterculture.

The English language has absorbed several words from his fiction, including "grok," meaning "to understand something so thoroughly that it becomes part of the observer." During his lifetime, beginning with his very first works in the later 1930s, he was also a major influence on many other writers, who tried to emulate, with varying degrees of success, the apparently effortless skill with which he blended speculative concepts and fast-paced storytelling.

Heinlein was born on July 7, 1907, to Rex Ivar and Bam Lyle Heinlein, in Butler, Missouri, United States. His father was an accountant. His childhood was spent in Kansas City, Missouri, where the family of seven lived in a two-bedroom house. The outlook and values of this time and place would influence his later works; however, he would also break with many of its values and social mores, both in his writing and in his personal life.

He attended the U.S. Naval Academy, graduated in 1929, and served as an officer in the United States Navy. He married his second wife, Leslyn Macdonald, in 1932. Little is known about his first marriage. Leslyn was a political radical, and Isaac Asimov recalled Robert during those years as being, like her, "a flaming liberal." Heinlein served aboard the USS Roper (DD-147) in 1933-1934, achieving the rank of Lieutenant.

In 1934, Heinlein was discharged from the Navy due to pulmonary tuberculosis. During his long hospitalization he conceived of the waterbed, and his detailed descriptions of it in three of his books later prevented others from patenting the idea. The military was the second great influence on Heinlein; throughout his life, he strongly believed in loyalty, leadership, and other ideals associated with the military.

After his discharge, Heinlein informally attended a few weeks of graduate classes in mathematics and physics at the University of California, Los Angeles, quitting because of either his health, a desire to enter politics, or both. He supported himself by working at a series of jobs, including real estate and – like Mark Twain – silver mining. Heinlein was active in Upton Sinclair's socialist EPIC (End Poverty In California) movement in early 1930s California. When Sinclair gained the Democratic nomination for governor of California in 1934, Heinlein worked actively for the unsuccessful campaign.

Heinlein himself ran for the California State Assembly in 1938, and was also unsuccessful. In later years, Heinlein kept his socialist past secret, writing about his political experiences coyly, and usually under the veil of fictionalization. In 1954, he wrote: "...many Americans ... were asserting loudly that McCarthy had created a 'reign of terror.' Are you terrified? I am not, and I have in my background much political activity well to the left of Senator McCarthy's position."

While not destitute after the campaign—he had a small disability pension from the Navy—he turned to writing to pay off his mortgage, and in 1939 his first published story, "Life-Line", was printed in Astounding magazine. He rapidly became acknowledged as a leader of the new movement toward "social" science fiction. He began fitting his early published stories into a fairly consistent future history, a chart of which editor John W. Campbell published in the May 1941 issue of Astounding, and which was later reprinted in his collection The Past Through Tomorrow.

During World War II he did aeronautical engineering work for the Navy, recruiting the young Isaac Asimov and L. Sprague de Camp to work at the Naval Aircraft Factory. As the war wore down in 1945, he began reevaluating his career. The atomic bombings of Hiroshima and Nagasaki and the outbreak of the Cold War galvanized him to write nonfiction on political topics, and he wanted to break into better-paying markets.

He published four influential stories for The Saturday Evening Post, leading off with The Green Hills of Earth in February 1947, which made him the first science fiction writer to break out of the pulp ghetto. Destination Moon, the documentary-like film for which he had written story, scenario, and script, and invented many of the effects, won an Academy Award for special effects. Most importantly, he embarked on a series of juvenile novels for Scribner's that was to last through the 1950s.

Heinlein was divorced from his wife Leslyn in 1947, and in 1948 married his third wife, Virginia "Ginny" Gerstenfeld, who undoubtedly served as a model for many of his intelligent, fiercely independent female characters. In 1953–1954, the Heinleins took a trip around the world, which Heinlein described in Tramp Royale, and which also provided background material for science fiction novels such as Podkayne of Mars that were set aboard spaceships.

Asimov believed that Heinlein made a drastic swing to the right politically at the same time he married Ginny. The couple formed the Patrick Henry League in 1958 and worked on the 1964 Barry Goldwater campaign, and Tramp Royale contains two lengthy apologias for the McCarthy hearings. However, this perception of a drastic shift may result from an inappropriate tendency to try to place libertarianism on the traditional right-left spectrum of American politics, as well as from Heinlein's iconoclasm, and unwillingness to let himself be pigeonholed into any ideology (including libertarianism).

The evidence of Ginny's influence is clearer in matters literary and scientific. She acted as the first reader of his manuscripts, and was reputed to be a better engineer than Heinlein himself. The political ideas in Heinlein's writing are discussed below under "Ideas, themes, and influence."

Heinlein's juvenile novels may have turned out to be the most important work he ever did, building an audience of scientifically and socially aware adults. He had used topical materials throughout his series, but his juvenile for 1959, Starship Troopers, was regarded by the Scribner's editorial staff as too controversial for their prestige line and was rejected summarily. Heinlein felt himself released from the constraints of writing for children and began to write "my own stuff, my own way," and came out with a series of challenging books that redrew the boundaries of science fiction, including Stranger in a Strange Land (1961), which is his best-known work, and The Moon Is a Harsh Mistress (1966), which many regard as his finest novel.

Beginning in 1970, however, Heinlein had a series of health crises, punctuated by strenuous work. The decade began with a life-threatening attack of peritonitis, recovery from which required more than two years. But as soon as he was well enough to write, he began work on Time Enough for Love (1973), which introduced many of the themes found in his later fiction. In the mid-1970s he wrote two articles for the Britannica Compton Yearbook.

He and Ginny crisscrossed the country helping to reorganize blood donation in the U.S., and he was guest of honor at a World Science Fiction Convention for the third time at Kansas City, Missouri in 1976. In 1977 he suffered a "near-stroke" because of a blocked carotid artery. He became exhausted, his health began declining again, and in 1978 he had one of the earliest carotid operations to correct the blockage.

Asked to appear before a Joint Committee of the U.S. House and Senate that year, he testified on his belief that spin-offs from space technology were benefitting the infirm and the elderly. His surgical treatment re-energized Heinlein, and he wrote five novels from 1980 until he died in his sleep on May 8, 1988, as he was putting together the early notes for his sixth "World As Myth" (Pantheistic solipsism) novel. Several of his works have been published posthumously.

Works

Early work, 1939–1960
The first novel that Heinlein wrote, For Us, The Living: A Comedy of Customs (1939), did not see print during his lifetime, but Robert James later tracked down the manuscript and it was published in 2003. Although a failure as a novel, being little more than a disguised lecture on Heinlein's social theories, it is intriguing as a window into the development of Heinlein's radical ideas about man as a social animal, including free love. The root of many themes found in his later stories can be found in this book.

It appears that Heinlein at least attempted to live in a manner consistent with these ideals, even in the 1930s, and had an open relationship in his marriage to his second wife, Leslyn. He was also a nudist; nudism and body taboos are frequently discussed in his work. At the height of the cold war, he built a bomb shelter under his house, like the one featured in Farnham's Freehold.

After For Us, The Living, he began writing novels and short stories set in a consistent future history, complete with a timeline of significant political, cultural, and technological changes. His collection The Man Who Sold the Moon offers a vertical timeline labeled "FUTURE HISTORY 1951-2600 A.D." with stories and novels located appropriately, lives of significant characters marked with vertical bars, and commentary. His full future history is compiled in two volumes: The Past Through Tomorrow and Orphans of the Sky. Subsequent authors such as Larry Niven have postulated future histories for their stories.

In Solution Unsatisfactory, written in 1940, Heinlein set out the following predictions: in 1941 the US government would start a large-scale secret project, which would make nuclear weapons available for use by the end of 1944 (radioactive dust rather than a bomb - but with much the same strategic implications); the weapon would be used to destroy an Axis city in 1945; this would bring WWII to an end, but start a nuclear arms race between the US and the Soviet Union. (In Heinlein's story, it leads to a new war which the US wins, gaining domination over the whole world but becoming a military dictatorship in the process).

Beyond the accurate prediction of specific events, "Solution Unsatisafactory" set out in advance the main arguments, dilemmas and mindsets of the Nuclear Age, which were to become enshrined in such terms and concepts as Nuclear Arms Race, Second strike or Mutual Assured Destruction. This, at a time when the whole issue was barely imagined even among most political and military decision-makers in the world.

Heinlein's first published novel, Rocket Ship Galileo, was initially rejected because going to the moon was considered too far out, but he soon found a publisher, Scribner's, that began publishing a Heinlein juvenile once a year for the Christmas season. Eight of these books were illustrated by Clifford Geary in a distinctive white-on-black scratchboard style. Some representative novels of this type are Have Space Suit—Will Travel, Farmer in the Sky, and Starman Jones.

There has been speculation that Heinlein's intense obsession with his privacy was due at least in part to the apparent contradiction between his unconventional private life and his career as an author of books for children, but For Us, The Living also explicitly discusses the political importance Heinlein attached to privacy as a matter of principle.

The novels that he wrote for a young audience are a fascinating mixture of adolescent and adult themes. Many of the issues that he takes on in these books have to do with the kinds of problems that adolescents experience. His protagonists are usually very intelligent teenagers who have to make a way in the adult society they see around them. On the surface, they are simple tales of adventure, achievement, and dealing with stupid teachers and jealous peers.

However, Heinlein was a vocal proponent of the notion that juvenile readers were far more sophisticated and able to handle complex or difficult themes than most people realized. Thus even his juvenile stories often had a maturity to them that make them readable for adults. Red Planet, for example, portrays some very subversive themes, including a revolution by young students modeled on the American Revolution; his editor demanded substantial changes in this book's discussion of topics such as the use of weapons by adolescents and the confused sexuality of the Martian character. Heinlein was always aware of the editorial limitations put in place by the editors of his novels and stories, and while he observed those restrictions on the surface, was often successful in introducing ideas not often seen in other authors' juvenile SF.

Many readers may not realize that some of Heinlein's apparently clichéd ideas, such as the voyage to the moon in Rocket Ship Galileo, were considered surprising at the time, and in fact helped to create the clichés in the first place. Another good example from this period is The Puppet Masters, which originated the idea of aliens taking over humans' bodies, as in Invasion of the Body Snatchers.

Heinlein's last juvenile novel, and probably his most controversial work in general, was Starship Troopers, which he wrote in response to the U.S.'s decision to unilaterally end nuclear testing. The book's main political idea is that there should be no conscription, but that suffrage should belong only to those willing to serve their society by two years of voluntary civil or military service.

Mature work, 1961–1973
From about 1961 (Stranger in a Strange Land) to 1973 (Time Enough for Love), Heinlein wrote his most characteristic and fully developed novels. His work during this period explored his most important themes, such as individualism, libertarianism, and physical and emotional love. To some extent, the apparent discrepancy between these works and the more naïve themes of his earlier novels can be attributed to his own perception, which was probably correct, that readers and publishers in the 1950s were not yet ready for some of his more radical ideas.

He did not publish Stranger in a Strange Land until some time after it was written, and the themes of free love and radical individualism are prominently featured in his long-unpublished first novel, For Us, The Living: A Comedy of Customs. Considered by many to be his best novel, The Moon Is a Harsh Mistress tells of a war of independence of Lunar colonies, with between-the-lines satire on the threat posed by any government -- including a republic -- to individual freedom.

Although Heinlein had previously written a few short stories in the fantasy genre, during this period he wrote his first fantasy novel, Glory Road, and in Stranger in a Strange Land and I Will Fear No Evil, he began to mix hard science with fantasy, mysticism, and satire of organized religion. Critics William H. Patterson, Jr., and Andrew Thornton believe that this is simply an expression of Heinlein's longstanding philosophical opposition to positivism.

Heinlein stated that he was influenced by James Branch Cabell in taking this new literary direction. The next-to-last novel of this period, I Will Fear No Evil, is according to critic James Gifford "almost universally regarded as a literary failure," and he attributes its shortcomings to Heinlein's near-death from peritonitis.

Later work, 1980–1987
After a seven-year hiatus brought on by poor health, Heinlein produced five new novels in the period from 1980 (The Number of the Beast) to 1987 (To Sail Beyond the Sunset). These books have a thread of common characters and time and place. They most explicitly communicated Heinlein's philosophies and beliefs, and many long, didactic passages of dialog and exposition deal with government, sex, and religion. These novels are controversial among his readers, and some critics have written about them with the intensity of a blowtorch.

Heinlein's four Hugo awards were all for books written before this period. Many feel that his later novels were not up to the quality of his earlier work; some have suggested the quality drop stemmed from his near-stroke in 1977. Heinlein's books of the 1980s sold well, in spite of some critics' lack of enthusiasm; many readers believe that those who criticize them are missing their irony and self-conscious parodying of both science fiction and literature in general.

Some of these books, such as The Number of the Beast and The Cat Who Walks Through Walls, start out as tightly constructed adventure stories, but transform into philosophical fantasias at the end. It is a matter of opinion whether this demonstrates a lack of attention to craftsmanship or a conscious effort to expand the boundaries of science fiction into a kind of magical realism, continuing the process of literary exploration that he had begun with Stranger in a Strange Land.

The tendency toward authorial self-referentialism begun in Stranger in a Strange Land and Time Enough For Love becomes even more evident in novels such as The Cat Who Walks Through Walls, whose first-person protagonist is a disabled military veteran who becomes a writer, and finds love with a female character who, like all of Heinlein's strong female characters, appears to be based closely on his wife Ginny.

The self-parodying element of these books keeps them from bogging down by taking themselves too seriously, but may also fail to evoke the desired effect in readers who are not familiar with Heinlein's earlier novels. Many readers are split on their reactions to Heinlein's wit, particularly in his dialogue -- characters from a plethora of milieus tend to favor the same midwestern-American, post-Depression style and referents. Some find it charming and disarming. Others attack it as unsophisticated.

Job: A Comedy of Justice is an overt satire of evangelical Christianity connected to his 1942 short story "The Unpleasant Profession of Jonathan Hoag." Like Job, Friday does not tie in to the other three self-referential novels but with the world of an earlier story, the 1953 novelette "Gulf."

Posthumous Publications
Four Heinlein works were published after his death — the aforementioned For Us, The Living as well as 1989's Grumbles from the Grave, a collection of letters between Heinlein and his editors and agent, 1992's Tramp Royale, a travelogue of a southern hemisphere tour the Heinleins took in the 1950s, and a tribute volume called Requiem, containing some additional short works never published in book form previously.

A fifth work, "Robert A. Heinlein's Variable Star" has been completed by Spider Robinson, a science fiction author who admits to being greatly influenced by Heinlein. It is scheduled for publication in October 2006.

Ideas, themes, and influence

Politics
Heinlein's writing may appear to have oscillated wildly across the political spectrum. His first novel, For Us, The Living, consists largely of speeches advocating the Social Credit system, and the early story "Misfit" deals with an organization which seems to be Franklin D. Roosevelt's Civilian Conservation Corps translated into outer space. Stranger in a Strange Land was embraced by the hippie counterculture, and Glory Road can be read as an antiwar piece, while Starship Troopers has been deemed militaristic, and To Sail Beyond the Sunset, published during the Reagan administration, is stridently right-wing.

There are, however, certain threads in Heinlein's political thought that remain constant. A strong current of libertarianism runs through his work, as expressed most eloquently in The Moon Is a Harsh Mistress. His early juvenile novels often contain a surprisingly strong anti-authoritarian message, as in his first published novel Rocket Ship Galileo, which has a group of boys blasting off in a rocket ship in defiance of a court order.

A similar defiance of a court order to take a moon trip takes place in the short story "Requiem." In The Moon Is a Harsh Mistress, the unjust Lunar Authority that controls the lunar colony is usually referred to simply as "Authority," which leads to an obvious interpretation of the book as a parable for the evils of authority in general, rather than the evils of one particular authority.

Heinlein was opposed to any encroachment of religion into government, and pilloried organized religion in Job: A Comedy of Justice, and, with more subtlety and ambivalence, in Stranger in a Strange Land. His future history includes a period called the Interregnum, in which a backwoods revivalist becomes dictator of the United States.

Positive descriptions of the military (Between Planets, The Moon Is a Harsh Mistress, Red Planet, Starship Troopers) tend to emphasize the individual actions of volunteers in the spirit of the Minutemen, while the draft and the military as an extension of government are portrayed with skepticism in Time Enough for Love, Glory Road, and Starship Troopers.

Despite Heinlein's work with the socialist EPIC and Social Credit movements in his early life, he was an ardent, lifelong anti-communist. In the political world of the 1930s (and other times), there was no perceived contradiction between being a socialist and being passionately anti-communist. Heinlein's nonfiction includes Who are the heirs of Patrick Henry? (an anti-communist polemic published as an advertisement) and articles such as Pravda Means Truth and Inside Intourist, in which he recounted his visit to the USSR and advised western readers on how to evade official supervision on such a trip.

Many of Heinlein's stories explicitly spell out a view of history which could be compared to Marx's: social structures are dictated by the materialistic environment. Heinlein would perhaps have been more comfortable with a comparison with Frederick Jackson Turner's frontier thesis. In Red Planet, Doctor MacRae links attempts at gun control to the increase in population density on Mars. (This discussion was edited out of the original version of the book at the insistence of the publisher.)

In Farmer in the Sky, overpopulation of Earth has led to hunger, and emigration to Ganymede provides a "life insurance policy" for the species as a whole; Heinlein puts a lecture in the mouth of one of his characters toward the end of the book in which it is explained that the mathematical logic of Malthusianism can lead only to disaster for the home planet. A subplot in Time Enough for Love involves demands by farmers upon Lazarus Long's bank, which Heinlein portrays as the inevitable tendency of a pioneer society evolving into a more dense (and, by implication, more decadent and less free) society. This episode is an interesting example of Heinlein's tendency (in opposition to Marx) to view history as cyclical rather than progressive.

Another good example of this is The Moon Is a Harsh Mistress, in which a revolution deposes the Authority, but immediately thereafter, the new government falls prey to the inevitable tendency to legislate people's personal lives, despite the attempts of one of the characters, who describes himself as a "Rational Anarchist."

Race
Heinlein grew up in the era of racial segregation in the United States and wrote some of his most influential fiction at the height of the U.S. civil rights movement. His early juveniles were very much ahead of their time both in their explicit rejection of racism and in their inclusion of non-white protagonists -- in the context of science fiction before the 1960s, the mere existence of dark-skinned characters was a remarkable novelty, with green occurring more often than brown.

For example, his second juvenile, the 1948 Space Cadet, explicitly uses aliens as a metaphor for human racial minorities: "That's just race prejudice. A Venerian is easier to like than a man." "...that's not fair...Matt hasn't got any race prejudice...Take Lieutenant Peters--did it make any difference to us that he's as black as the ace of spades?" In this example, as in books written throughout his career, Heinlein challenges his readers' possible racial stereotypes by introducing a strong, sympathetic character, only to reveal much later that he is of African descent.

This also occurs in, e.g., The Cat Who Walks Through Walls and Tunnel in the Sky; in several cases, the covers of the books show characters as being light-skinned, when in fact the text says that they are dark-skinned or of African descent. The Moon Is a Harsh Mistress and Podkayne of Mars both contain incidents of racial prejudice or injustice against their protagonists. Heinlein repeatedly denounced racism in his non-fiction works, including numerous examples in Expanded Universe.

Race was a central theme in some of Heinlein's fiction. The most prominent example is Farnham's Freehold, which casts a white family into a future in which white people are the slaves of Black rulers. In the 1941 novel Sixth Column (also known as The Day After Tomorrow), a resistance movement defends itself against an invasion by an Asian fascist state (the "Pan-Asians") using a "super-science" technology that allows ray weapons to be tuned to specific races.

The idea for the story was pushed on Heinlein by editor John W. Campbell, and Heinlein wrote later that he had "had to reslant it to remove racist aspects of the original story line" and that he did not "consider it to be an artistic success." Some readers may mistake Heinlein's dislike of communist China for a dislike of Asians, or misinterpret negative depictions of overpopulation in Asia in Tunnel in the Sky and Farmer in the Sky as general criticism of Asian civilization.

Good and bad people are to be found among all races in Heinlein's fiction. For example, in Sixth Column, a Japanese-American heroically sacrifices himself in the fight against the invaders. In The Star Beast, a harried African bureaucrat is sympathetically portrayed as the behind-the-scenes master of the world government, while a white sheriff in rural Colorado is parochial and prejudiced.

Some of the alien species in Heinlein's fiction can be interpreted in terms of an allegorical representation of human ethnic groups, but this is often risky. Double Star, Red Planet, and Stranger in a Strange Land all deal with tolerance and understanding between humans and Martians. Several of his stories, such as Jerry Was a Man, The Star Beast, and Red Planet, involve the idea of nonhumans who are incorrectly judged as being less than human.

Although it has been suggested that the strongly hierarchical and anti-individualistic "bugs" in Starship Troopers were meant to represent the Chinese or Japanese, Heinlein wrote the book in response to the unilateral ending of nuclear testing by the U.S., so it is more likely that they were intended to represent communism. The slugs in The Puppet Masters are likewise explicitly and repeatedly identified as metaphors for communism. A problem with interpreting aliens as stand-ins for races of homo sapiens is that Heinlein's aliens generally occupy an entirely different mental world than humans.

For example, an alien race depicted in Methuselah's Children, the Jockaira, are sentient domesticated animals ruled by a second, godlike species. In his early juvenile fiction, the Martians and Venerians are usually depicted as ancient, wise races who seldom deign to interfere in human affairs.

Individualism and self-determination
Many of Heinlein's novels are stories of revolts against political oppression, for example:

1. Residents of a lunar penal colony, aided by a self-aware computer, rebel against the Warden and Lunar Authority (and eventually Earth) in The Moon Is a Harsh Mistress.
2. Colonists rebel against Earth in Between Planets and Red Planet, and in the back story to Podkayne of Mars.
3. Secularists overthrow a religious dictatorship in "If This Goes On—".
4. A group of soldiers take on the mantle of power after the governments of the world break down as part of the back story in Starship Troopers.

But in keeping with his belief in individualism, his more sophisticated work for adults often portrays both the oppressors and the oppressed with considerable ambiguity. In Farnham's Freehold, the protagonist's son accepts the security that comes with being castrated. In Glory Road, a monarch is depicted positively, and in The Star Beast, a publicity-shy bureaucrat is sympathetically portrayed as the behind-the-scenes decision-maker behind the planetary government.

In The Moon Is a Harsh Mistress, prerevolutionary life under the Lunar Authority is portrayed as a kind of anarchist or libertarian utopia; projections of economic disaster are the true (and secret) justification for the revolution, which brings with it the evils of republican government. Novels such as Stranger in a Strange Land and Friday revolve around individual rebellions against oppression by society rather than by government.

Heinlein believed that individualism did not go hand-in-hand with ignorance. He believed that an appropriate level of adult competence was achieved through a wide-ranging education, whether this occurred in a classroom or not (as in Citizen of the Galaxy). In his juvenile novels, more than once a character looks with disdain at a student's choice of classwork, saying "Why didn't you study something useful?" In Time Enough For Love, Lazarus Long gives a long list of capabilities that anyone should have, ending with "Specialization is for insects."

The common thread, then, is the struggle for self-determination of individuals, rather than of nations. The ability of the individual to create himself is explored deeply in stories such as I Will Fear No Evil, "—All You Zombies—", and By His Bootstraps. We are invited to wonder, what would humanity be if we shaped customs to benefit us, and not the other way around? In Heinlein's view, as outlined in For Us, The Living, humanity would not only be happier, but perceptually, behaviorally, and morally aligned with reality.

Sexual liberation
For Heinlein, personal liberation included sexual liberation, and free love was a major subject of his writing starting from the 1939 For Us, The Living. Beyond This Horizon (1942) cleverly subverts traditional gender roles in a scene in which the protagonist demonstrates his archaic gunpowder gun for his friend and discusses how useful it would be in dueling — after which the discussion turns to the shade of his nail polish. "—All You Zombies—" (1959) is the story of a person who undergoes a sex change operation, goes back in time, has sex with herself, and gives birth to herself.

Sexual freedom and the elimination of sexual jealousy are a major theme of Stranger in a Strange Land (1961), in which the straitlaced nurse Jill acts as a dramatic foil for the less parochial characters Jubal Harshaw and Mike. Over the course of the story, Jill learns to embrace her innate tendency toward exhibitionism, and to be more accepting of other people's sexuality (e.g., Duke's fondness for pornography).

As discussed in more detail in the book's article, two brief negative references to homosexuality have been interpreted by some readers as being homophobic, but both deal with Jill's hang-ups, and one is a discussion of Jill's thoughts. Homosexuality is treated with approval — even gusto — in books such as the 1970 I Will Fear No Evil, which posits the social recognition of six innate genders, consisting of all the combinations of male and female with straight, gay, and bisexual.

In later books, Heinlein dealt with incest and the sexual nature of children, topics that, Freud notwithstanding, touch a raw nerve with many readers. In Time Enough For Love, Lazarus Long uses genetic arguments to dissuade a brother and sister he's adopted from sexual experimentation with each other (and later arranges for them to be married), and consummates his strong sexual attraction to his own mother, whom he goes back in time to rescue.

In some of his books, To Sail Beyond the Sunset for instance, a young girl climbs into her father's lap or bed, but he kicks her out. In the same book, when the protagonist is unable to dissuade two of her teenage children from having a sexual relationship, she washes her hands of them, sends them to their father, and never mentions them again. The protagonist of The Cat Who Walks Through Walls recalls a homosexual experience with a Boy Scouts leader, which he didn't find unpleasant.

In Heinlein's treatment of the possibility of sex between adults and children, some readers may feel that he dodges many of the valid reasons for the taboo by portraying the sexual attractions or actual sex as taking place only between Nietzschean supermen, who are so enlightened that they can avoid all the ethical and emotional pitfalls.

Perhaps the greatest form of sexual liberation found in Heinlein's work, from first to last, was his treatment of females. Beginning with For Us, the Living and Life-Line, Heinlein's female characters of all ages were generally competent, intelligent, courageous, powerful and in control of their lives and situations to whatever extent the circumstances permitted.

Those few of his female characters who were weak or helpless are held in contempt by other characters (including other females). It does not denigrate these competent females to note that part of their agenda was generally to marry the best man they could find (quite often the book's hero).

Philosophy
In To Sail Beyond the Sunset, Heinlein has the main character, Maureen, state that the purpose of metaphysics is to ask questions: Why are we here? Where are we going after we die? (and so on), and that "you are not allowed to answer the questions". Asking the questions is the point for metaphysics, but answering them is not, because once you answer them, you cross the line into religion. Maureen does not state a reason for this; she simply remarks that such questions are "beautiful" but lack answers.

The implication seems to be as follows: because (as Heinlein held) deductive reasoning is strictly tautological and because inductive reasoning is always subject to doubt, the only source of reliable "answers" to such questions is direct experience — which we do not have. Maureen's son/lover Lazarus Long makes a related remark in Time Enough For Love. In order for us to answer the "big questions" about the universe, Lazarus states at one point, it would be necessary to stand outside the universe.

During the 1930s and 1940s, Heinlein was deeply interested in Alfred Korzybski's General Semantics and attended a number of seminars on the subject. His views on epistemology seem to have flowed from that interest, and his fictional characters continue to express Korzybskian views to the very end of his writing career. Many of his stories, such as Gulf, "If This Goes On—", and Stranger in a Strange Land, depend strongly on the premise, extrapolated from the Sapir-Whorf hypothesis, that by using a correctly designed language, one can liberate oneself mentally, or even become a superman.

He was also strongly affected by the religious philosopher P. D. Ouspensky. Freudianism and psychoanalysis were at the height of their influence during the peak of Heinlein's career, and stories such as Time for the Stars indulged in psychoanalysis. However, he was skeptical about Freudianism, especially after a struggle with an editor who insisted on reading Freudian sexual symbolism into his juvenile novels.

He was strongly committed to cultural relativism, and the sociologist Margaret Mader in his novel Citizen of the Galaxy is clearly a reference to Margaret Mead. In the World War II era, cultural relativism was the only intellectual framework that offered a clearly reasoned alternative to racism, which Heinlein was ahead of his time in opposing. Many of these sociological and psychological theories have been criticized, debunked, or heavily modified in the last fifty years, and Heinlein's use of them may now appear credulous and dated to many readers. The critic Patterson says "Korzybski is now widely regarded as a crank," although others disagree.

Influence
Heinlein is usually identified, along with Isaac Asimov and Arthur C. Clarke, as one of the three masters of science fiction to arise in the so-called Golden age of science fiction, associated with John W. Campbell and his magazine Astounding. However, in the 1950s he was a leader in bringing science fiction out of the low-paying and less prestigious pulp ghetto.

He was at the top of his form during, and himself helped to initiate, the trend toward social science fiction, which went along with a general maturing of the genre away from space opera to a more literary approach touching on such adult issues as politics and human sexuality. In reaction to this trend, hard science fiction began to be distinguished as a separate subgenre, but paradoxically Heinlein is also considered a seminal figure in hard science fiction, due to his extensive knowledge of engineering, and the careful scientific research demonstrated in his stories.

Heinlein's influence extends to hundreds of science fiction and general fiction authors, including later notables like techno-thriller writer Tom Clancy and science-fiction writers John Ringo, Eric Flint, and David Weber.

Outside the science fiction community, several words coined or adopted by Heinlein have passed into common English usage: waldo, TANSTAAFL, and grok. He was influential in making space exploration seem to the public more like a practical possibility. His stories in publications such as The Saturday Evening Post took a matter-of-fact approach to their outer-space setting, rather than the "gee whiz" tone that had previously been common.

The documentary-like film Destination Moon advocated a Space Race with the Soviet Union almost a decade before such an idea became commonplace, and was promoted by an unprecedented publicity campaign in print publications. Many of the astronauts and others working in the U.S. space program grew up on a diet of the Heinlein juveniles, as shown by the naming of a crater on Mars after him, and a tribute interspersed by the Apollo 15 astronauts into their radio conversations while on the moon. Heinlein also was guest commentator for Walter Cronkite during Neil Armstrong's Apollo 11 moon landing.

Quotations

"Men rarely (if ever) managed to dream up a god superior to themselves. Most gods have the manners and morals of a spoiled child."

"History does not record anywhere or at any time a religion that has any rational basis. Religion is a crutch for people not strong enough to stand up to the unknown without help. But, like dandruff, most people do have a religion and spend time and money on it and seem to derive considerable pleasure from fiddling with it."

"The most preposterous notion that H. sapiens has ever dreamed up is that the Lord God of Creation, Shaper and Ruler of all the Universes, wants the saccharine adoration of His creatures, can be swayed by their prayers, and becomes petulant if He does not receive this flattery. Yet this absurd fantasy, without a shred of evidence to bolster it, pays all the expenses of the oldest, largest, and least productive industry in all history."

"Any priest or shaman must be presumed guilty until proven innocent."

"Theology is never any help; it is searching in a dark cellar at midnight for a black cat that isn't there."

"Theology is never any help; it is searching in a dark cellar at midnight for a black cat that isn't there."

"Anyone who can worship a trinity and insist that his religion is a monotheism can believe anything ... just give him time to rationalize it."

"The faith in which I was brought up assured me that I was better than other people; I was saved, they were damned.... Our hymns were loaded with arrogance -- self-congratulation on how cozy we were