By JANET MASLIN

It is 3 p.m. in the New York office of Keith Richards’s manager. Mr. Richards has a 3 o’clock appointment. “Come on in, he’ll be here in a minute,” an assistant says - and here he comes in a minute, at 3:01.

This from a man who once prided himself for operating on Keith Time, as in: the security staff ate the shepherd’s pie that Keith wanted in his dressing room? The Rolling Stones don’t play until another shepherd’s pie shows up. Chalk up the promptness to the man’s new incarnation: he is now the distinguished author of “Life,” a big, fierce account of the Stones’ nearly half-century-long adventure.

“It’s the most difficult thing I’ve ever done,” he says about the book. “I’d rather make 10 records.” He sounds anything but weary. Today, in neutral street clothes and hotgreen shoes, he is positively debonair. On his head: a headband and a raffish, straw-colored hat, gray tufts of hair poking out . Not a single trinket hangs off it. “I’ve been through that phase,” he says. He’s been through a lot of phases.

And they’re all in “Life”: the Boy Scout (really); the tyro rocker; the lovestruck kid (mad for Ronnie Spector ); the astonished new star; the heroin- addicted older one; the longtime sparring partner of Mick Jagger.

The book’s single biggest stunner is a hand-written note on its jacket flap: “Believe it or not, I haven’t forgotten any of it.” “I think my main concern at the beginning was whether my memory was really reliable,” he says. James Fox, the journalist and author of “White Mischief,” who has been Mr. Richards’s friend over many years, was his collaborator on “Life.”

He researched Mr. Richards’s past, conducting interviews and drawing upon old letters and journal entries. “Spent day practising,” the 19-yearold Mr. Richards wrote in January 1963 . “Worthwhile, I hope!” Also exhumed: a 1962 letter from Mr. Richards to his Aunt Patty describing a boy he had known in primary school, Mick Jagger.

These artifacts prompted recollections . Once his stories were told and a draft was written, he and Mr. Fox wound up sitting together with separate copies of the manuscript as Mr. Fox read the whole book aloud. “What I couldn’t guess was that he’d be such a very good natural editor,” Mr. Fox says of Mr. Richards. “He cut, accordingly, for pace and rhythm ? a real musical cut.

” The book begins with a 1975 drug bust in Arkansas and a judge who was persuaded to free Mr. Richards after confiscating his hunting knife (which still hangs in the courtroom) and having a picture taken with him.

It covers many other arrests too, as well as Mr. Richards’s grueling efforts to kick his heroin addiction, which he claims to have done successfully 30 years ago. “Stories like this aren’t told very much,” he insists. “There aren’t many people willing to tell them.” “Life” has already attracted undue attention for a juvenile-sounding anatomical insult to Mr. Jagger.

But this is a book that doesn’t hold back, and most of its insults are more serious. “Cold-blooded” and “vicious” are two words he uses to describe Brian Jones.

Allen Ginsberg was an “old gasbag.” Donald Cammell, the film director (“Performance,” starring Mr. Jagger and Anita Pallenberg, Mr. Richards’s longtime lover ), couldn’t commit suicide quickly enough to suit Mr. Richards. (He shot himself in 1996.) When Marlon Brando propositioned him and Ms. Pallenberg, Mr. Richards remembers replying , “Later, pal.” As for Mr. Jagger, the complaints involve self-promotion, social climbing, egomania, insecurity and uncertain sexual identity.

There’s also a cool condescension about Mr. Jagger’s contributions to the duo’s songwriting. “It’s bound to be somewhat rough, but the point is I’m trying to tell the story from Day 1 to now,” Mr. Richards says. He did see to it that Mr. Jagger knew what was in the book . Some of the book’s most surprisingly revelatory material appears in what Mr. Richards calls “Keef’s Guitar Workshop.

” Here are the secrets of some of the world’s most famous rock riffs and the almost toy-level equipment on which they were recorded, like the cassette recorder onto which Mr. Richards dubbed guitar layers for “Street Fighting Man,” “Jumpin’ Jack Flash” and part of “Gimme Shelter.” Here’s how the silent beats in Elvis Presley’s “Heartbreak Hotel” worked their way into some of his most inspired solos.

Mr. Richards is the rare memoirist who can say, without hyperbole, “that what I hoped was worth sharing with people turned out to be far more important than I could possibly imagine.”