As the 1960s generation ages and begins to disappear, it might have seemed natural that the death grip which the decade holds on the American imagination would start to loosen. Nearly 40 years after the summer of love, however, the ’60s have not quite faded into history. Instead, like a few other decisive epochs — the revolutionary 1790s, the low, dishonest 1930s — they have graduated into memory, serving as a repository of symbol and emotion for people who never lived through them. The ’60s still matter because they reveal certain possibilities of human nature in extreme form: above all, the beauty and danger of utopianism. For the ahistorical children of the American Empire, the ’60s held out the same hope, and offered the same chastening lesson, that Wordsworth found in the French Revolution, when he witnessed “France standing on the top of golden hours, / And human nature seeming born again.”

In his new memoir, “Prime Green” (Ecco, 240 pages, $25.95), Robert Stone recognizes this cousinship between the decades. “As the poet wrote, it was good to be alive and to be young was even better,” he writes, wryly misquoting “The Prelude”: “Bliss was it in that dawn to be alive / But to be young was very heaven!” Yet in the true spirit of the ’60s, Mr. Stone immediately goes on to disavow the parallel, claiming for his own time that unfathered authenticity which it valued above everything: “More than the inhabitants of any decade before us, we believed ourselves in a time of our own making.” To a romantic of the 1960s, it is impossible to keep the lessons of the romantic 1790s in mind, for the very reason that romanticism is drunk on originality. So the same follies and errors have to be committed again, the same lessons learned, or ignored. “We learned what we had to, and we did what we could,” is Mr. Stone’s final verdict on his generation’s adventures, a verdict of innocence that still refuses to acknowledge that radical innocence might itself be a kind of guilt.

Yet if Mr. Stone is one of the best writers to emerge from the 1960s, it is largely because he did not and does not buy into the decade’s illusions wholesale. The true visionaries of the ’60s from Allen Ginsberg to Mr. Stone’s close friend Ken Kesey, believed that transformation — of the self, the soul, and the world — was imminent, and could be hastened by their antinomian pranks. Mr. Stone, however, is not a visionary but an artist, and his novels are unsparing studies of a madness he does not share. From his masterpiece, “Dog Soldiers,” in 1974, down to his most recent book, “Bay of Souls,” in 2004, Mr. Stone has been a diagnostician of the maladies of innocence — the sickness that William Carlos Williams had in mind when he wrote that “the pure products of America go crazy.”

After those dark and penetrating novels, “Prime Green,” Mr. Stone’s rollicking, picaresque new memoir, can’t help seeming a little evasive, even though it hews closer to the facts of his own life. Mr. Stone is on record as disliking and distrusting autobiography — “Escaping from yourself is one of the purposes of fiction for me,” he told an interviewer in 1997 — and even now that he is writing his autobiography, the unease remains. Nothing is pressed too closely in “Prime Green,” including the author himself; not only are there no confessions, there are not even any hard questions. Instead, there is a catalog of good yarns, honed by years of repetition into a professional’s act. Not until the act is over do you realize the performer has slipped away.

“Prime Green” opens in 1958, when Mr. Stone was a 21-year-old sailor on board a ramshackle transport in the Antarctic. His nearest approach to combat, he writes, came when the ship’s guns were trained on a mysterious vessel that turned out to be an enormous colony of migrating penguins. This story of disappointed adventure, of harmless, comic futility, sets the keynote for many of the anecdotes to come. Mr. Stone is tempted to abandon his pregnant wife and join a bizarre Christian vaudeville troupe, but he resists the temptation and stays home. He is menaced by sailors on a Greyhound bus, who take exception to his protohippie costume, and even though he does get beaten up, it feels like an anticlimax compared to the surreal violence of Mr. Stone’s own novels.

The aimlessness of Mr. Stone’s stories is not unrelated to the fact that many, all too many, of them involve drugs. As the 1950s turn into the 1960s, we see Mr. Stone get married too young, start a family, work menial jobs, and struggle to finish his first novel. Amid these responsibilities, drugs — from pot to peyote — beckon like the lotuses on Circe’s island, promising a respite that all too easily becomes a prison. “Prime Green” powerfully communicates the sheer monotony of the druggie ’60s, the amount of time and attention devoted to scoring drugs, getting high, and puzzling out the visions that ensued. Social encounters, at least as Mr. Stone recounts them here, are devoid of anything like civilized pleasure; we hear nothing about conversation, only the alternating monologues of the stoned. “One party I attended,” Mr. Stone recalls, “featured a human cat’s cradle. ‘All the thumbs raise their hands,’ called the Kentucky folklorist who was our founder.” It is a party one is not sorry to have missed.

The real mystery of “Prime Green,” the one Mr. Stone never satisfactorily answers, has to do with what drew him to such milieus in the first place. A true artist and a genuinely liberal spirit — why could he find no better companions than the crank Kesey or the intolerable Neal Cassady? To answer that question would mean delving much deeper into Mr. Stone’s early years, of which he gives only a fleeting and disturbing glimpse. (A New York native who grew up saying “youse” and “dose,” Mr. Stone writes that he was raised by a mentally ill mother and spent several years in an orphanage.) At the same time, it would mean confronting the illusions of the ’60s, which in their challenge to American civilization ended up promoting a kind of barbarism.”Prime Green” does not go out far or in deep enough for that, but it still deserves to be read, if only as a collection of tales from a master storyteller.

akirsch@nysun.com