Heinlein might be best known for his body of work known collectively as the Future History series.

In discussing those books, I have two problems: how to define the Future Histories, and how to discuss an ongoing series without giving away a lot of things that should be surprises.

Let's tackle the first one. Heinlein's own idea was that the universe represented in his stories should be consistent; he created charts and time lines tracking when things happened in various stories. This would allow a story set in 1980 and another set in 2100 to share the same historical past in which Leslie LeCroix was the first person on the Moon, in 1965.

This is an entirely accurate way to view the Future Histories; the main problem with it is that is encompasses pretty much all his stories, whether they take place in the same century, whether any of the characters ever meet.

However, particularly toward the end of his life, Heinlein shaped a specific set of tales in which there are many continuing characters and story lines; it is easier to see them as actually constituting a "series," and it is these interrelated stories that fans have come to know as the Future Histories series.

As I mentioned in my discussion of Heinlein's general works, there is much disagreement about which stories are Future Histories. I'm not out to insist that I've included them all; a dozen more novels and short stories could be included easily. A good example of a story many might include here is Misfit, from the collection Revolt in 2100, which is the story in which Andy Libby first appears. Libby's introduction is certainly important, but I just couldn't bring myself to include that brief story here, so it's discussed along with the other non-Future History stories.

I also hesitated to include The Rolling Stones here because the story itself is much more like one of Heinlein's "juveniles" than the others I've included. However, Hazel Stone first appears in The Rolling Stones. Based on the fact that it is a novel and not a short story, and based on how large a part Hazel actually plays in that book and much later in The Cat Who Walks Through Walls, I felt that The Rolling Stones did in fact belong on this list.

My list of Future Histories is an attempt to cover the basics, to show the origins of most people who become major characters or events that later are important. That list is as follows:

• The Rolling Stones (1952)
• Methuselah's Children (1958 revised version of earlier serialized material)
• Stranger in a Strange Land (1961)
• The Moon Is a Harsh Mistress (1966)
• Time Enough for Love (1973)
• Number of the Beast (1980)
• The Cat Who Walks Through Walls (1985)
• To Sail Beyond the Sunset (1987)

As far as that second problem I mentioned -- discussing a series without giving away too much -- well, I give up. I'm just going to discuss each book, in order, and do my best.

So BE WARNED: some details of the following stories might be ruined for you if you read on without having read the books!

The Rolling Stones (1952) is one of the stories usually classed as "juveniles," although it's an entertaining read for adults as well.

It's the story of the Stone family and how they decide to leave their home in Luna for a nice long vacation trip -- to Mars, the asteroid belt, wherever.

The Stones consist of Roger and Edith Stone and their kids Meade, the twins Castor and Pollux, and little Lowell -- and, most importantly, The Rolling Stones serves to introduce Roger's mother, grandma Hazel Stone, one of the "founding fathers" of Luna.

Methuselah's Children (1958) is a key early work to understanding the Future Histories. It introduces the "Howard Family," not an actual family but a group of people produced by a breeding program fostered by the Ira Howard Foundation.

What's special about the Howards is that they are longer lived than "normal" people -- and have kept this a secret for two centuries through changing identities and relocating.

In 2125 the secret is leaked, and the Howards are being persecuted by the rest of the world. Rather than submit to being rounded up by the government for questioning and who knows what else (medical torture to extract their "secret," perhaps), they instead steal an enormous starship and make their escape.

Lazarus Long, the most important figure in the Future Histories, makes his entrance here. Andrew Jackson Libby is also aboard the starship (making engineering innovations the whole way).

One of the breakthroughs in Methuselah's Children comes as a result of the world's conviction that the Howards are actually hiding the scientific secret to long life rather than harboring it in their genes. So convinced, scientists attempt to duplicate the Howards' results, and come up with revitalizing therapies that allow even non-Howards to live significantly longer and healthier lives. Using "rejuvenation" therapy themselves, Howards can live almost indefinitely.

Whole books could be written about Stranger in a Strange Land (1961), which probably is Heinlein's most famous work.

In Stranger, Heinlein uses an outsider's eyes to examine American culture and religion. The outsider in question is Valentine Michael Smith, and he's an outsider by virtue of having been born on Mars to parents who were scientists and astronauts.

"Mike" was the only survivor of the Mars mission -- and he was adopted as a baby by Martians, was raised and taught by them, and thought he was one of them until a later mission "rescues" him as a young man.

Eventually, after being adopted by nurse Jillian Boardman and doctor/lawyer/writer/curmudgeon Jubal Harshaw on Earth, Mike sets out to thoroughly understand modern culture -- which inspires him to spread the Martian philosophy -- which road eventually leads to martyrdom.

The Moon Is a Harsh Mistress (1966) is one of my favorite Heinlein books and a fascinating immersion into another culture -- that of the Lunar colony on the verge of the revolution for independence from Earth. Heinlein does a great job of creating a jargon or dialect for the colonists, which includes Australian and Russian lingo.

The narrator is Manuel Garcia O'Kelly. Early in the story it's established that Manny is a computer programmer and repairer and one of his clients is the massive computer the Administration uses to run the whole Moon -- and the computer has somehow become self-aware.

Manny, along with his friend the computer (named Mike), lady friend Wyoming Knott, and Professor Bernardo de la Paz, ends up orchestrating the revolution to free Luna.

A very interesting aspect of this story, which begins in May 2075, is that we meet a 12-year-old Hazel Meade -- she who will later be Hazel Stone. As we are told that Hazel is 95 years old in The Rolling Stones, this settles the date of that work as well.

With Time Enough For Love (1973), the Future History gets increasingly complicated. I often wonder whether Heinlein intended to write an additional book in the series to take place before Time Enough, because he skips to -- get this -- the year 4272, an outrageous leap most authors would take only to show futuristic humans evolved into nothing but big brains with tentacles.

Obviously, a lot has taken place in all that time. Andy Libby's development of faster-than-light travel in Methuselah's Children has allowed "the Diaspora," the colonization of empty, healthy planets and the further downfall of an overpopulated and overexhausted Earth. The Howards formed their own government on Secondus, and of course wherever Howards go there spring up Rejuvenation Clinics.

As Time Enough opens, Lazarus Long, now well over two thousand years old by virtue of genetics and rejuvenation, is being held against his will at the Secondus clinic -- held because, as the most senior member of the Howards, he is a priceless resource and a hero; against his will because this rogue, the oldest living human, has finally tired of life and wants no part of further rejuvenation (if a Howard goes long enough without rejuvenating, he'll eventually die of old age like anybody else).

While saving his physical life, clinic officials and the Howard Chairman get to know Lazarus and struggle to present him with new, exciting goals to live for while they learn about his long and varied life.

During the course of the book Lazarus and newfound loves marry and found the Long family. Lazarus tells stories, some entertaining and some -- notably "The Tale of the Adopted Daughter" -- quite moving.

After various adventures both past and present, Lazarus begins a program of recreational time travel, back to the era of his childhood, early 20th century Kansas City, Earth. In a series of events that affects all the stories to come, he actually falls in love and has a moving and tormented affair with his own mother, Maureen, telling her that he is a Howard, is from the future, and is descended from her, but omitting that he is in fact her own son.

More or less inadvertantly, Lazarus gets mixed up in World War I, and although his future family rescues him, wounded, from the battlefield, he is officially missing in action, presumed killed, back in Maureen's time.

The Number of the Beast (1980) is one of my favorite Heinlein novels, and that's saying a lot. The story begins with a bang, followed quickly by a double honeymoon. The main characters in the beginning are the two couples: professor, inventor, genius, and widower Jacob; his bride and old family friend lovely, brilliant Hilda; Jake's daughter, red-haired computer-genius sexpot Deety; and Deety's new acquaintance and husband, smart, competent beefcake Zebediah.

Jake invented a time machine, and in its first test drive it turned out to actually allow travel between the universes (which turns out to be incredibly convenient for Heinlein, if a little incomprehensible at times). Next thing you know, aliens are trying to discredit Jake's work and kill the whole family to prevent said universe-hopping, and the family's on the run.

In their travels, the family discovers many things, one of which is that "Jake's space-time twister" actually allows travel to universes they had thought of as fictional, like Lewis Carroll's Wonderland and Baum's Oz. (To my disappointment, they discuss Middle Earth, but don't end up finding it. Maybe it's not in the public domain.)

In their explorations, the family finally encounters the space yacht Dora -- Lazarus Long's ship. To them, as to us, it had been fiction. They meet the Long family and hear Lazarus' request -- he's read about them, too, and arranged to meet him in hopes that they would help him rescue his mother, Maureen, using Jake's invention.

It seems that Maureen was reported killed in a traffic accident back in 1980 -- decades after her affair with her time-traveling son -- and Lazarus hopes to snatch her safely from that accident and bring her into his family. The original two couples are also invited to marry into the fold and become Longs.

This is where the cast of characters becomes too complicated for me to recount. (By the way, my tally puts the Long family at some 28 humans and four computers by the end of To Sail Beyond the Sunset.) This is also where Number of the Beast gets confusing. Its last section features a multi-universe convention and jamboree attended by the Longs; Jubal Harshaw and others from Stranger in a Strange Land; adventurous Hazel Stone and her twin grandsons; and minor characters from a host of other Heinlein stories, including I Will Fear No Evil, Glory Road, Podkayne of Mars, and Between Planets (naming them and their stories of origin is a popular challenge among Heinlein enthusiasts). During this section, incidentally, Jubal and Hazel decide to accept rejuvenation, something they'd both refused before.

The final section is what keeps this book from being more popular even among big Heinlein fans, I think. It's confusing and full of Heinleinian jokes and puns that are difficult to understand. However, Number of the Beast is the work that allows the final Future History books to happen.

Perhaps what I find most appealing about it is the four new, main characters. Most of the book alternates narration duties among the four, so one really gets to know them intimately. Heinlein does a masterful job of looking at the same situations through four different minds and really brings depth to Jake, Hilda, Zeb, and Deety. Hilda remains one of my favorite Heinlein characters, although I don't want to start any contests!

The next-to-last Future History is 1985's The Cat Who Walks Through Walls, subtitled A Comedy of Manners. (You might recall that JOB was subtitled A Comedy of Justice.)

Cat Who Walks begins by introducing us to Richard Ames, also known as Colin Campbell, and his girlfriend Gwen Novak, both of whom live in orbiting Golden Rule Habitat in the year 2188. They get married on page 15 (when Heinlein characters decide to get married, they don't screw around with a long engagement).

The outward story line is that a mysterious stranger who interrupted Richard and Gwen's dinner by invoking a kind of password from Richard's secret past gets killed right there in the restaurant, and Richard sets out to find the killer while Gwen secretly sets out to recruit Richard for a Time Corps mission.

The Time Corps was formed by the Long family, more or less, after the big jamboree at the end of The Number of the Beast. Jake's space-time twister not only makes it possible to travel among the universes, its Libby modification makes time travel possible and also makes it possible to create universes and time lines by changing something in the "past," which is what the Time Corps selectively does.

Turns out that a lot of weird things happen to Richard while he's finding out Gwen's secret agenda. People are mysteriously killed, and Gwen and Richard are blamed. The two are kicked out of their homes and encounter all sorts of incivility and inconvenience. Also, Richard is disturbed when Gwen tells him she's not really this Gwen Novak person -- her real name, she says, is Hazel Stone Long. Richard has heard of Hazel, who's famous, and he's known Gwen for some time, so he's deeply concerned about her identity crisis.

Eventually Richard believes that Gwen is really Hazel. The mission the Time Corps wants him for, she explains, is the rescue of the computer Mike, leader of the Lunar revolution in The Moon Is a Harsh Mistress and personal friend of Hazel's adoptive father Manny.

After being attacked and injured, the two are rescued and taken to the Long home on Tertius; while Richard recovers, he meets all the Longs, including Lazarus, whom he dislikes on sight and who tries to bully him into agreeing to the rescue mission. (He also meets Pixel, the cat who walks through walls, and is adopted by him.)

Finally, after finding out a family secret, Richard agrees to the mission, but it ends in one of Heinlein's only cliffhangers. The mission seems to succeed, and the party escapes except for three gravely wounded members: Richard, Hazel, and, sadly, Pixel. At the end of the book Richard fades in and out of consciousness, tries to tend to the other two, and waits for rescue.

To Sail Beyond the Sunset (1987), the master's last novel, is subtitled The Life and Loves of Maureen Johnson (Being the Memoirs of a Somewhat Irregular Lady).

This book is largely the autobiography of Lazarus' mother, Maureen, dictated while she's lost and waiting for the family to rescue her. (With her is a grown-up and fully recovered Pixel, by the way.) What isn't revealed until near the end is that Maureen got lost while, like Lazarus before her, she was scheming a way to rescue from the past her most beloved parent, her father Ira Johnson. (Also like Lazarus before her, Maureen was always in love with the parent she most resembled.)

While that tale -- redemption of lost love after a lifetime of thinking it was impossible or too late -- is interesting and poignant (and somewhat inevitable), it is Maureen's whole life story that really provides the attraction.

Maureen was born July 4, 1882, to a large family, had an extremely happy childhood, married young to Brian Smith, who became the father of Lazarus and many others, raised children and kittens, and had lots of sex.

Particularly interesting is her narrative of her romance with Lazarus, not knowing he's her son, and her grief at his loss in the war. I also find her telling of her rescue and rejuvenation, and finding out that Lazarus is indeed her own favorite son Woodrow Wilson Smith, very touching. After all, Maureen thought her lover from the stars was dead for most of a century.

Maureen is a much-beloved character among Heinlein fans, the respected matriarch of the Future History saga, a fine, fun person, and a sexpot beyond compare, and her autobiography is very welcome.