BOOK REVIEW : Captivating Voice of an Obsessed Heroine Expends Itself Too Soon : MATING <i> by Norman Rush</i> ; Alfred A. Knopf; $23, 485 pages

The narrator of “Mating” is witty, raunchy and vulnerable, prodigiously aspiring and discursive. She is a woman warrior whose charges are braver for the trepidation with which they’re conducted, whose self-knowledge pricks air leaks in her balloons, and whose myopia blurs the self-knowledge and keeps her veering.

The heroine of “Mating”--set, like Norman Rush’s previous book, “Whites,” in Southern Africa--is a captivator. She is 32, good-looking and sexy, though running to a few extra pounds. Rush has endowed her with a voice that is, for a while, irresistible. We follow it gladly, until we notice that it seems to lead us around in circles.

The center of these circles is a Great Man. He is Nelson Denoon, an anthropologist of world repute, great glamour and considerable mystery, with whom the narrator--herself a student in the field--falls in love. It is more than love, though; it is hero worship and a determination to be his lover, disciple, amanuensis and muse.

“He was so famously sardonic! So heretical! He was so interdisciplinary,” the narrator tells us. The book’s pungency rises out of this odd mix of enthusiasm and self-aware irony. Continually, she manages to lose her head and keep it at the same time. The effect is highly unstable.

“Mating” tells of her pursuit of Denoon to a utopian community he has founded in a remote corner of Botswana, of the time she spends there, and of the untidy upheavals that shake up the community, drive Denoon to nervous collapse, and shatter the relationship.

The book begins with a narrator returning to Gabarone, Botswana’s capital, after a solitary year in the bush researching a dissertation on food-hunting cycles. It hasn’t worked out, and she declares herself ready for rest and recreation in what the white expatriates call “Gabs.”

She is able to meet Denoon on one of his rare trips back from the interior. He gives a private lecture on solar power. “Every day a great machine goes back and forth and pours out treasure that nobody takes in his hands,” he pronounces, arguing that solar energy can turn villages into idyllic “engines of rest.” Denoon is against imported technologies and ideologies; he champions village development using locally devised methods and techniques.

The narrator asks to return with him to Tsau, the community he has invented. He refuses regretfully--there is considerable mutual attraction--so she makes a brutal solitary trek across the Kalahari Desert to get there. Half-dead on her arrival, she is taken in, healed and gradually accepted.

Tsau is a community of women. Denoon believes that rural development requires women to run things. Accordingly, they hold all the property and all the local authority. The few men are there on sufferance. On the other hand, of course, Denoon--male guru and mentor--is the exception to his own rule.

The narrator joins in the village labors: Farming, construction, tending the solar panels and going on snake patrols. She moves in with Denoon, and before long, they become lovers.

The greater part of “Mating” consists of the narrator’s account of Tsau, on the one hand, and of Denoon on the other. Rush’s utopia is suggestive at times, but on the whole it is rather dull. Even when it breaks down--a faction turns against Denoon after a whispering campaign by a South African-influenced agent--its story lacks the ingenious detail that utopian narratives require if they are to compensate for their didactic message.

The book’s emotional center is Denoon; or rather, the narrator’s obsession with him. She recounts in exhausting detail their conversations, jokes, domestic habits, sex life and ideological explorations. She even recounts his dreams; more than that, she analyzes them.

It is decidedly too much of a good thing. It is like having someone praise a friend at such length and detail that, without meeting him, you detest him. We do meet Denoon and he is noble, clever, weak and unstable, but he is never very vivid. He disappears under the narrator’s torrent of opinions, starry-eyed and patronizing by turns.

In many ways, “Mating” is a remarkable book. Rush’s notions about African culture, its problems and the distorting influence of the West--as voiced by the narrator and, through her, by Denoon--are stimulating and subtle. His protagonist is a memorable female character; a continually shifting prism that revolves from dashing to needy, from witty to morose. She is larger than life; she is also larger than her own life and, as with large feet in tight shoes, stumbles in it.

Her major defect, though, is also the book’s. Her voice, so wonderfully varied and pungent, expends itself and finally makes itself tedious as it tries and fails to establish the magical, though frail, magus figure that it celebrates.

Next: Elaine Kendall reviews “ The Mommy Club “ by Sarah Bird (Doubleday).