In all the noise about sex in our world, "The Joy of Sex," revised, has sneaked back onto the shelf, sort of chaste and soft and quiet for all its explicitness, 30 years after the original and nearly three years since the death of its author, a British gerontologist and poet named Alex Comfort.

"Whatever revisions we made were definitely written in my father's spirit," says Nick Comfort, his son. "The book is a classic, and in a sense the message is timeless. Good sex assists communication and makes relationships better. It's a theme that runs through the whole thing."

Alex Comfort's illustrated 1972 lovemaking guide was such a phenomenal bestseller, for so long, that there was a time you could locate a copy in or near almost any married couple's bedroom, but you had to be crafty about it. You had to flip through it really fast. If you were 12 years old, you should never have looked. Never, ever.

But you looked.

No one credits this book (along with Judy Blume's advanced oeuvre) with doing what most junior high school health curricula didn't -- showing you the blueprints. On a virginal encounter with "The Joy of Sex" you had to be doing something wrong -- snooping in the master bedroom while baby-sitting for the people down the street, for example.

It was almost always there if you looked hard enough, usually in a cubbyhole of the water-bed headboards of the day: a 7-by-10-inch paperback, with a plain yellow or white cover, red lettering, and inside, everything you didn't want to know about sex, everything you wouldn't even dream of asking. So long, childhood mystery; hello, Mr. and Mrs. Fleetwood Macrame Neanderthal.

They lived large, those two, and the whole of sixth grade seemed to know them. The man had a beard, long hair and wasn't circumcised. (And has since gone on to mythic status across the pond, a ready punch line for one British comedian, who refers to him as "The Hairy Man.") His companion, everyone recalls, didn't shave her armpits. Together they changed the world with great sex.

Can the world now be changed again?

No. It's too late. Even Ellen Goodman, the op-ed priestess of feminist prudence, has more or less recommended that you bone up on the 30th-anniversary redux of "The Joy of Sex" as a stepping-off point to teaching kids something cable TV hasn't learned 'em already.

Alex Comfort's book was once revolutionary, emerging from a Britain that had only just loosened its stiff anti-pornography laws, and quickly catching on in America. Comfort fell hard for the swinging '70s and relocated himself and his second wife to the Southern California nexus of switchy clubs. Up until his death in 2000 at age 80, he had been tinkering with "The Joy of Sex" enough that newer versions have seemed progressively more sober. In a "Girls Gone Wild" realm, the book now seems horse-sensical about getting it on.

The new one retracts some of Comfort's dated proselytizing for free love. With HIV on the loose, it's done a 180 on the wisdom of condoms, which after the Pill struck Comfort as a supreme nuisance. Anal sex is strongly discouraged now.

Since its re-release last fall, "The Joy of Sex" has demurely taken its place on Barnes & Noble self-help shelves larded with its Children of Eden: racier guides to G-spots, how-to's for unending tantric orgasms, solicitous bondage advice for beginners. There are even coffee-table picture books of fetishes, and all of this mere steps away from the science-fiction section and Harry Potter displays. Sex books are always well thumbed; it's hard to make a bestseller of them now.

About 130,000 copies of the new "Joy of Sex" have been ordered worldwide since last fall -- but it remains to be seen how many will ultimately be purchased. The good news, however, is that Ireland hasn't banned it this time, and neither have all those countries behind the former Iron Curtain, where it used to get smuggled in with jeans and candy bars. "The Joy of Sex" remains the world's modern Kama Sutra, translated into dozens of languages.

This time around, the book is a labor of a different kind of love, a tender tribute from a son who wanted to honor his father's memory. It's an altogether other form of joy.

"We didn't want to change more than we had to," says Nick Comfort, 57, who cared for his ailing father for a decade leading up to his death. Although Alex updated "The Joy of Sex" several times, he had never tackled a complete revision.

It was up to Nick -- a former political journalist who now advises Scotland's secretary of state to the British cabinet -- to work with publishers on "The Joy of Sex" (new subtitle: "Fully Revised and Completely Updated for the 21st Century"), and it was Nick who chose to leave his name off his father's best-known work.

"It's still my father's book," he says from his restored 12th-century home in Oxfordshire, England, where he lives with his second wife, Corrine, and 8-year-old son, Alex. Nick is now preoccupied with writing three books of his own -- one about public relations, one about the construction of the Channel Tunnel, and a British political dictionary -- but he can't escape "The Joy of Sex's" iconic status worldwide.

Though Alex Comfort gave the world a taste of sexual positions and techniques with exotic and ridiculously French nicknames -- negresse, croupade, flanquette -- Nick Comfort recalls that, as a teenager, he got no more guidance in the facts of life from his father than other kids did from their dads. While in boarding school, Comfort heard his father on the radio promoting the distribution of condoms to teenage boys. Mortified, Nick remembers just wanting to know how to meet girls; nevermind how to skillfully apply pattes d'araignee to their most private spots.

He was 26 when "Joy" first came out, and still stung by his father's affair and divorce from his mother. While Nick worked as a White House correspondent in Washington, Alex became a celebrity sex guru. "I never got an invitation to visit my father and stepmother when they lived in California," Comfort says. "They were into the swinging scene at the time and didn't want to put me on the spot. But we were always on the phone with one another."

Only in later years did father and son find new connections. Alex returned to England. Nick had a son and named him Alex, who grew close to his grandfather. (The younger Alex is now repeating a family tradition of being teased about his father's pet project: In response to his own son's first questions about sex, Nick replied, "It's how men and women get on with each other." Nick repeated that in media interviews about the book, and it wasn't far from People magazine to his son's playground. "Kids pick up on things more quickly, and I think he's taken a fair amount about it at school," Nick says.)

The new version of the book has a royal purple cover, same dimensions, hardback, with much of Alex Comfort's text intact. The major change is the banishment of Hairy Man, with illustrations that feature softer lines and buffer bodies -- although "soft" seems to be the only word to describe the sexual aesthetics of the family Comfort. In addition to the drawings, there are now erotic color photos, somewhere between a Victoria's Secret ad (sans undies) and a soft-core, very special episode of "Once and Again."

The elder Comfort's sexual sensibilities are still with us: "The Joy of Sex" implores us not to trim our body hair, not to use deodorant, to broaden our definitions of "normal" and limit our concept of "dirty." If we're really hung up on hygiene, "Joy" recommends a good bidet. Hairy Man may be gone, but his hippie spirit lives.

Hairy Man, in origin, was Charles Raymond, the original book's art director. After several botched attempts to illustrate the book, Raymond and his wife, Edeltraud, performed more than 100 sex acts while Chris Foss, the illustrator, took Polaroids. In a BBC documentary on Alex Comfort's life and work, Foss recalled:

"Edeltraud was very Germanic and 'Right, Charles, we start now. Position number one!' She'd tap her leg and say, 'Come on, Charles!,' and off they would go and do that and she would tick it off and say, 'Right, Charles, now we do this one!' It was the icy winter of the miners' strike. The lights would suddenly go off, but Charles and Edeltraud were generating their own electricity."

So a legend was born. Nick Comfort now has to deal with the questions. (Always there will be questions; there is no "everything" you wanted to know about sex.) A Japanese reporter wants him to list all the new sexual positions that have been invented since the first edition came out. "I told him I think the last one was invented 9,000 years ago," Comfort says. There was also the French writer who demanded to know what, if anything, the French could learn from a sex manual written by an Englishman.

The elder Comfort always wanted people to discover the answers for themselves, together, without the clutter of pop culture dictating body image or prowess. One editor suggested pepping up Comfort's old text with current references to pop culture. "They suggested adding a reference to 'The Full Monty,' " Nick Comfort says.

"I'm glad I was able to give them an answer. That was one of the last movies my father ever saw. He hated 'The Full Monty.' "

The "Hairy Man" and his mate, left, of the original "Joy" have been replaced by a buffer couple for the 21st century.