Almost a Man : SACRED COUNTRY: By Rose Tremain : (Atheneum: $21; 322 pp.)

“The soul’s sojourn in the body is an illness,” Aristotle said. Our estrangement, not only inside our bodies but inside our lives, is a ground theme of religion, philosophy and literature. It lives in warring conjunction with such other themes as “We are our bodies” and, more universally, “We are our lives.”

In Rose Tremain’s cranky and continually unexpected new novel--though all her novels are unexpected and considerably alluring--Aristotle is quoted by Edward Harker, an old craftsman who makes England’s best cricket bats in his damp cellar. He quotes it to comfort his unhappy young visitor, who says she is living in the wrong body. An ardent believer in reincarnation, he further consoles her by observing that the Angel of Forgetfulness, whose job it is to make people forget their previous existence, is quite often forgetful himself.

Mary Ward, Harker’s visitor and teen-aged neighbor, is the daughter of a despairing, hard-drinking farmer in England’s fen country. Her mother is in and out of a mental hospital; Mary has been convinced since the age of 6 that she is not a girl.

Mary’s entrapment in a woman’s body, and what she does about it in her sparky, reflective and rebellious fashion, provide the main story in “Sacred Country.” But entrapment and identity are seen more largely. Mary’s father thinks of himself as an old English yeoman cultivating a green and pleasant land. Instead, he is trapped in poverty and wrests sugar beets, hideous as toads, out of the mud and into a failing market. Her mother is a light and fugitive soul trapped in a sullen home. Mary’s brother, Tim, whose spirit soars as a boy chorister and floats as an adolescent team-swimmer, is trapped among his father’s muddy beets. And Walter Loomis, a young neighbor who knows himself to be a country-and-western singer, is trapped cutting meat in the ancestral butcher shop.

Most, though not all, will escape in a fashion that possesses more gaiety than believability. The gaiety is not indulgent or sentimental; it has its terrors. As for the believability, this is not quite the point.

Tremain conveys reality--a craftsman’s workshop, how rain falls in East Anglia, and the psychological counseling that underpins a sex-change operation--very well indeed. But she is not a realistic novelist. Like her characters, she will not be confined by her body. She is a teller of philosophical tales, winningly disguised under human countenances, raincoats and errands; and a happy ending is not a sentimental device but a means of lightening the mind for the next round.

Tremain’s prose is gnome-nibbled. Behind the signposted doors of her sentences there are unseen gulps, giggles or odd, suggestive rustles. The book opens with King George VI’s deathin 1952. At 2 p.m., all England will observe a one-minute silence to mourn it. “They wept not merely for the king but for themselves; for the long ghastly passage of time,” Tremain writes loftily, and with a pinprick of irony. Immediately, she hits ground: “On the Suffolk farms a wet snow began to fall like salt.”

And then, the absurd particulars. Sonny and Estelle Ward, 6-year-old Mary and little Tim stand out in the field, getting wet. Sonny is waiting for 2 o’clock sharp; unfortunately, the minute hand on his watch had fallen off. He insists on praying outdoors to provide a direct route upward. “He said the people of England owed it to the wretched king to speak out for him so that at least he wouldn’t stammer in Heaven.” And it was just then that Mary, in purple mittens, round fogged glasses and legs protruding from her too-small coat, realizes that she is a man.

It seems absolutely right and not in the least a non sequitur. If I knew why, I would be writing novels instead of reviewing them: something about the purple mittens and the lost minute-hand. We are not what the world dresses us up as.

There are more than a few practical difficulties for a 6-year-old farm girl who insists she is male. Sonny, who had doted on her until Tim was born, abuses her savagely. In one terrible scene, he tears off the bandage with which she has bound her adolescent breasts and beats her into a weeping huddle. Yet Mary never doubts herself or, rather, her right to find out who she is. She calls herself Martin, and falls passionately in love with another schoolgirl, yet when she grows up and has a brief affair with a lesbian, she realizes that she is not this, either. “She could only love women who love men,” Tremain writes.

She is a man--almost. Yet at the book’s end, when she has gone to live in Tennessee--Walter, the unwilling butcher, has taken his guitar to Nashville, married a backup singer and become a very minor Opry star, complete with rhinestone jacket--she stops her surgery short of a total sex change. “Sacred Country” is not about sex or happiness but about identity. Mary/Martin finds hers/his just short of total transsexualism, and quite alone.

Mary’s story is superficially bizarre, yet Tremain makes her not just real but moving and blithe. Opposite to most writers, the author starts at extremities and moves toward a center. Not all her characters get there. Tim, who leaves the beets for the priesthood, is odd and schematic. Walter is not entirely right, either, though sometimes Tremain gets him to dazzle. In love with a chilly local girl, he is unable to impress her. “Loving Sandra is like being the moon and trying to warm the sky,” she writes.

Tremain illuminates her strugglers from a circle of unexpected torch-bearers. Half a dozen old men and women, variously eccentric and free, here and there suggest that the soul can escape its circumstances. Harker the woodworker, Mary’s grandfather, her old teacher and others intervene at odd moments to keep the younger characters from taking root.

There is a hint of the magical or providential at work. Occasionally, Tremain’s elderly deities arrive ex-machina. But she is rooted in the English pantheistic tradition; mostly, she lodges them in the idiosyncrasies, the gnarled features and quirky purposes of her geezer-Titans.