Deferential Calculus : THE THEORY OF EVERYTHING <i> By Lisa Grunwald (Alfred A. Knopf: $20; 325 pp.)</i>

Both fiercely contemporary in its time and place--Manhattan in the early ‘90s--and fabulistic in its structure--the spiritual journey of a young scientist--Lisa Grunwald’s “The Theory of Everything” combines fate with psychology. The result is a post-Freudian version of “The Odyssey.”

In spiritual journeys, the traveler usually begins at the apex of his worldly success, at the moment when he’s got the most but still feels incomplete. He begins the journey with the sense that something still is missing from his life, and it ain’t another Oscar.

In this case, Alexander Simon has just cracked an astounding formulation of higher mathematics that has led him to a ground-breaking “theory of everything.” The world of physics lauds him. He has worked toward this moment for many years, thinking it would answer his need to unlock the secret of the universe, or “to know everything,” as his mother once told him grown-ups did. Now he would finally find happiness and peace. Instead, he feels panicked and depressed. He’s gone as far as he can in the direction of his intellect. His theory of everything treats existence on a subatomic level; it has no effect on the world as we know it.

What makes the fable a novel is Alice, Alexander’s mother. She abandoned Alexander and her husband Sam 20 years earlier to pursue a course of spiritualism and magic, stuff that Alexander contemns. But Alexander is haunted by memories of a ghost that he thinks he once saw at his mother’s bidding, and dreams of an angel who teases him with the hope of total knowledge.

In suppressing his rage at his mother, and his hurt, Alexander has suppressed anything in him that resembles her, namely the strongly spiritual, irrational sides of his own nature. Alice returns to New York to meet Alexander on his 31st birthday, just when his own malaise at having discovered the theory of everything has set in. Alice introduces Alexander to Cleo, and soon Alexander is following a new course, the way of alchemy, to discover a more satisfying “theory of everything”: the Prime Matter.

Lisa Grunwald can really tell a story. Her fictive gifts, which in this case are driven by a system of signs that approaches allegory, buoy up the whole narrative, so that you feel at every moment the solidity of real people, real events. Her novel makes you feel that life itself functions on the two planes of simple, conscious living and the dark, irrational existence ruled by the mysteries of the moon, the imagination, the spirit, the unconscious.

“The Theory of Everything” is a map of dark and light, moon and sun, Dionysian and Apollonian impulses. Translated into contemporary drama, Alexander’s life is split between sunning himself on the roof of his girlfriend’s apartment and waiting and brooding in the dark subway tunnel; between Sam, his scientist-father, and Alice, his spiritualist mother; between Linda, his loyal, loving girlfriend who teaches grade school, and Cleo, his paramour, a palm-reader who lives by magic. Even his two “bosses” have an opposing symmetry: Dr. Biner, the physicist, and Harold, the alchemist.

Grunwald’s tone charms the reader. She makes you feel safe no matter how threatening the subject matter. Because she dates most episodes, you feel the “journal entry” effect of the novel, as if we are reading the records of a great late-20th-Century explorer. She wants you to know what Alexander knows, and goes to considerable effort to convey the mind-numbing concepts of physics, which she herself, by the way, has researched--the book actually includes a bibliography.

Of course, since Alexander is a genius, she does run into the “Star Trek” problem: namely, she’s created a character like Mr. Spock, who is by definition more brilliant than his creator. She has privileges into Alexander’s mind, so that we can see how his constant frame of reference is mathematical. For instance, she writes, “He had taken the contents of a package of Pepperidge Farm Goldfish and was arranging them on his desk in ever-widening circles. Physicists and mathematicians played a similar game in their heads, called sphere packing: How many spheres could fit inside one sphere . . . . This was the kind of question that brought physicists endless joy and debate.”

Or, when Alexander feels a conflict between his attachments to Linda and Cleo: “His mind kept shifting from Cleo to Linda and back again. A slight change in focus, and the whole world changed. It was like looking at a cube drawn on paper; stare at one set of right angles, and then the front becomes the back; stare at the other set, and then the back becomes the front.” The textbook optical illusion: Are these the thoughts of a genius?

Grunwald is a fearless writer, one who takes on the most daunting outreaches of human thought and uses them as story elements, character points or turns of plot. Her people are firmly planted. For instance, Cleo is fabulously raunchy as a cigarette-smoking model-turned-palm-reader, and Harold has a sly craving for chocolate-chip cookies.

If the book has a weakness, it is in spite of Grunwald’s people.

The solitary quest that Alexander embarks on loses dramatic force as we dip into our hero’s latest esoteric text with him, find ourselves making perfume with him, or staring at the moon with him. Yes, he finally can experience things as they are, without reflexive analogies to mathematics, but the enlightenment falls short of satisfaction. It’s anticlimactic, and when Alexander makes his final decisions, we are less exalted than relieved to escape from a certain literary tedium.

Even if Grunwald’s generous impulse to “share the magic” doesn’t always work, her skill at creating interesting human dilemmas and seeing them through does. In her first novel, “Summer,” she examined the painful experience of a daughter watching her mother die; here, she traces a son’s struggle to accept the loss of his mother. In both books, Grunwald shows how and where and why life may be affirmed.

She has a nose for the surprises, for the secret traps that nature sets for its human creatures, tricking them again and again into living.