THIS REMARKABLE BOOK has an equally remarkable genesis. When Norman Mailer was working on The Executioner's Song, his book about the violent life and death of Gary Gilmore, he received a letter from a convict named Jack Abbott, warning Mailer that "very few people knew much about violence in prisons." Abbott soon made it clear that he was one of the very few. He had ample opportunity: since the age of 12, Abbott, now 37, had spent all but nine-and-a-half months behind bars, where he had himself killed a fellow inmate, had witnessed and been subjected to violence as unrelenting as it was unjust. With Mailer's encouragement, Abbott offers to share this awful knowledge, and in doing so finds his vocation as a writer; this against all the odds shapes his life, thereby redeeming it from a brutality our imagination can hardly grasp.

Abbott's passionate survival, his redemption of a seemingly hopeless life, is the buried narrative of In the Belly of the Beast. These letters do not themselves contain much narrative (although what there is has a mysterious, off-center power -- tales of murder, suicide, sexual entreaty) but are largely made up of scorching analytical "essays" on the varieties of punishment devised for the inmates, on the particular horrors of solitary confinement, on the absolute eveil of the prison guards' behavior. Yet at one point Mailer evidently tried to praise Abbott for his "story," for the shape his life was taking. Abbott, however, is made uncomfortable with this "literary burden, and responds to Mailer with elegant under-statement:

"I've never kept a diary, but the closest I came was my letters to you. My life is not a 'saga' and I resent your using the term like that. I do not feel 'heroic.' But I am caught in an experience of life not the subject of common dissertation. You expressed an interest in it. I meant to accommodate that interest to the fullest of my abilities."

Abbott's editor at Random House has wittingly or unwittingly conspired with him to make the least of the narrative possibilities of this "saga": the letters are fragmentary, undated, and arranged without regard to chronology but according to "subject." None of Mailer's letters is included, an understandable editorial decision, but the result is the loss of another narrative dimension, to be found in the give and take and growing intimacy of their correspondence.

But the reader, ever hungry for narrative and story, has a way of going against the wishes of the best-intentioned editor and even the writer himself, in focusing on "an experience of life not the subject of common dissertation," in keeping Abbott's life at the center of his attention. And when Abbott follows his instincts as a writer in dealing with these overwhelming experiences he instinctively stays center stage; the clear eye and steady hand are a writer's eye and hand as Abbott achieves something like an heroic accuracy and detachment, whether he is describing the vivid shock of "dull prison-blue" after the sensory deprivation of a stay in solitary or rendering in almost nauseating detail the sensation of wielding the knife as it enters another's body. What one presumes to be a motive in Abbott's rejecting the heroic role in a saga -- an overriding concern with justice, revolution, ideals transcending the merely personal -- is fortunately abandoned in the intensity of this observation. He brings the same acute powers of seeing to more general analysis, as when he examines the poisonous relationships between inmate and inmate, between inmate and guard.

But to my mind the richest, most touching perceptions in these letters are those recordings, made in rueful wonder, of the relation between mind, language, thought, emotion, and experience. The extraordinary circumstances of Abbott's life have made him regard these phenomena with a vision unfogged by the easy habits and distractions of "normal" life.

On emotion, for instance: because he is "state-raised," in prison from childhood, he is aware of "a whole spectrum [emotion]" that he knows "only through words, through reading and my immature imagination. I can imagine I feel those emotions . . . But I do not. At age thirty-seven I am barely a precocious child. My passions are those of a boy."

On on thought: "I've only lately discovered that at age thirty I began to exercise the ability to think . . . It is funny; that some of us must also know all the details of the world before we venture out into it. Only now do I feel I know enough to live."

If this is not the stuff of myth, what is? And what is Abbott's account of solitary confinement if it is not seen as a terrible, literal enactment of ritual, the planned, conscious, infinitely cruel playing out of the human condition at the extremes of possibility?

"A man is taken away from other prisoners, from his experience of other people, when he is locked away in solitary confinement in the hole.

"Every step of the way removes him from experience and narrows it down to only the experience of himself.

"There is a thing called death and we have all seen it. It brings to an end a life, an individual living thing. When life ends, the living thing ceases to experience.

"The concept of death is simple: it is when a living thing no longer entertains experience.

"So when a man is taken farther and farther away from experience, he is being taken to his death."

When Abbott sees and thinks and writes with this direction, we are lucky witnesses to the authentic making of a writer.

But there is another Abbott. He served five-and-a-half years in Maximum Security, and it was during those years he educated himself, "with only my books and my balls and a punishment set of white standard (five sizes too large) coveralls. Novels and dictionaries. And then philosphy, until it came out of my ears." Bohr, Hertz, Hegel, Nietzche, Kierkegaard, Russell, Whitehead, Carnap, Quine. "It all found expression -- and came together in the most elegant sense -- in the findings of Marx," and that is where the difficulties with the other Abbott start, for this reader at least. Abbott's instincts as a writer desert him, or he suppresses them, as he draws back from what is before his eyes and indulges himself in unattached speculation, in the rant of the preacher, the demagogue. After chastising Mailer, in the passage cited above, for calling his life heroic, Abbott goes on to say, "I never preached to you, nor tried to convert you. My respect would not allow that. Besides, I know more than most the futility of debate in such matters." When did he write that to Mailer? There's no way to tell, given the editorial practices described earlier, but it doesn't gibe with the last 70 pages of this 166-page book, pages on which Abbott makes statements such as "the communist press always tells the truth in reporting events in prison," or "Men have pled guilty to murder and have been executed without anyone asking them the simple question: Why? In no other country on the face of this earth do such injustices exist today. There is no tyranny this profound in any country but America."

This Abbott, with absurd or wrongheaded opinions on American society outside prison, on racism outside prison, on sexuality and homosexuality outside prison, on politics, foreign policy, Russia, China, Cuba, anything under the sun -- this Abbott caused me to squirm with embarrassment, not simply because I think some of his opinions are foolish -- we are all stuffed with foolish opinions that we windily dispense at will -- but because of the pathos that marks them, the pathos of a man doggedly determined to assert his knowledge of a world he has never been allowed to know. (Now, according to the press, he will have his chance: Abbott has been granted a parole.)

But this latter part of the book, given pride of place by editorial fiat, shouldn't allow us to forget the astonishing spectacle we have already encountered: a man living out a nightmare life, a demonic parody of what the real world knows as a life, who not only survives injustice and oppression and worse but through strength of mind and will comes to understand his life and make something worth having from it -- a saga, an heroic story despite all disclaimers.