The Isolated Man : Through pride and rage, an AIDS patient’s body rises up to kill him : WALKING ON AIR, <i> By R. S. Jones (Houghton Mifflin: $21.95; 253 pp.)</i>

The book starts with the crack of mortality’s whip.

“His body terrifies him,” the author writes of William, who has begun to die of AIDS. “His mind has trained the body to follow its commands: to sit, to stand, to lie down like a pet. He can flex its muscles, swing its arms, make it jump, contort it in almost any direction. Sometimes he likes to test the body’s limits, to cut it, scrape it, bend its fingers until each one crackles with pain.

“But even then he is only marooned on its surface. He can truly know nothing but its skin, its hair, its visible scars, the blue blush of its veins. Underneath, the body is a mystery of vessels, muscles, bones, a whole galaxy of parts as secret as the darkest star shrouded in clouds of deadly gas.”

William’s body is rising up to kill him, and before this relentless fictional journal of disintegration ends, it more or less will. R. S. Jones’ first novel, “Force of Gravity,” was an oddly tender and lively novel about a man who abandons the lethal anonymities of city life to find a far more human world as an attendant in a mental hospital. In “Walking on Air,” he has produced something harsher and colder.

The link of opposites between the two titles is not without significance. The earlier book suggested the life that flowers in a state that many of us would consider not much better than death. This one, even though it is about dying, locates death not in the awful melting down of William’s body but in the life he has chosen for himself. “Gravity’s” protagonist journeys on a path of humility. “Air’s” William sticks motionless in pride.

The book begins with a brief moment from William’s childhood in the Southwest; the rest consists of periodic glimpses over the year and a half that extends from the lethal diagnosis to the end, with passages touching on his life in New York before falling ill. He had become a wealthy stockbroker with a country house on eastern Long Island; a man with two friends, many acquaintances, and a sex life consisting of pickups in a West Village gay bar.

He is without a family or, rather, he had cut himself off from it. The beautifully written opening passage depicts the harsh ranch-life in which he was raised, and spotlights a single scene: helping his father slaughter a pig in the pre-dawn darkness. Later, he fled the rigor, rigor embodied above all in the animal’s terrible death-scream. (In a brilliant moment near the end, the ravaged William will give the same scream.) He was fleeing the crudeness of biological life and death, the carnal rise and fall of a family’s generations; he wields his homosexual condition as an aloofness, a token of exemption.

Instead, over the years, he has conscripted Susan, an unmarried woman of his own age--40 or so--and Henry, a young teacher. “Friends are family,” he decrees, and in different ways he holds the two in uneasy subjection through their own vaguely acknowledged needs. Susan seems to see in William some of the certainties of her dead father. Henry, who met William in a sexual encounter that immediately turned platonic, sees in him a confident assertiveness that shields him from having to make his own choices. William’s wealth also seems to offer a security, and the older man dangles the promise that some day he will leave Henry his country house.

Two submissions, each with elements of rebellion. And when William telephones Henry and Susan that he is going to die, submission becomes a yoke. In the hospital he demands daily attendance; temporarily at home, he insists on continual rounds of errands and company. As he gets sicker the demands increase as does his own fury at being dependent and fear that he will be abandoned.

The account of physical disintegration is appalling: fevers, rashes, dozens of tumors, a swill of secretions, the flesh literally bursting open, seizures, partial blindness. There are the desperate recourses: a visit to a psychic, a televised faith healer--the proud William gets down on his knees only to have a commercial interrupt--a specialist who dabbles in a new blood treatment.

Both friends feel their life being taken over; perhaps less by William’s bottomless needs than by his bottomless demands. Susan finds a lover through the personals column; Henry, discovering that William has lied about making a will and leaving him his house, feels betrayed and, for a while, stops visiting. Only at the end, in William’s final dying state, does Henry come back to nurse him to the end.

Jones has written an abstract morality tale as much as a novel. William has no human identity except autocratic pride, fear and rage. Even healthy, he was a wraith. As for Henry and Susan, they could as well be called First Friend and Second Friend for any particularity they possess apart from their relation to William.

The abstraction serves the author’s purpose, up to a point. William’s outrage at the rebellion of his body, his anguish at losing sovereignty over his flesh and fate, his resentment that others will live while he dies, are certainly part of a human condition far broader than the particular horrors of AIDS. People have been dying for a long time--many horribly, as Sherwin Nuland recently reminded us in “How We Die”--and refusal goes back almost as far. For instance, there is the Icelandic epic of Snorri, the man of limitless prowess, whose last words as the spears enter his body are: “It shall not be!”

But of course there are other aspects to being human. Are our bodies us? There is a children’s book, “Brave Mr. Buckingham,” in which a not-very-handyman manages successively to chop, saw or snip off arms, legs and everything else he possesses, each time chortling: “ That didn’t hurt.” Do the awful-to-read indignities that eat William away annul his life or only end it? You don’t need a religion to believe that life is something beyond our collection of toes, forearms, genitals, large intestines and so on.

It takes life, in any event, to make death more than a hellish outrage. William’s turning away from mortality and human claims, when he turned away from his family and turned toward no one in its place, makes a dying into a damnation. Contrary to that powerful quote at the start, it is, finally, not a matter of the body rising to deny the mind but of the mind, over a lifetime, relinquishing to the body the power to do so.