And This Shall Be a Sign : A MAN WITHOUT WORDS, <i> By Susan Schaller Foreword by Oliver Sacks, MD (Summit: $17.95; 189 pp.)</i>

In his foreword to Susan Schaller’s new book, Dr. Oliver Sacks (“Awakenings,” “The Man Who Mistook His Wife for a Hat”) asks readers to imagine a child who is “not only deaf but born in a place or a country where education is not mandatory; suppose he never meets another deaf person, is never exposed to proper sign language; what then? He may grow into adolescence, and even to adulthood, without any language --a human being, perhaps a gifted one, deprived of what all the rest of us take for granted, deprived of the essentially human birthright of language.”

About a decade ago, 24-four-year-old Susan Schaller encountered a languageless Mexican immigrant named Ildefonso when she showed up for an interpreting job at a poorly run reading-skills class in Los Angeles. What she walked into was something between a fiasco and a scandal: “Why had they hired me, a sign-language interpreter, for an all-deaf class with a signing teacher?”

What made her stay was the sight of a 27-year-old man for whom the chaotic class was particularly useless: “There was bewilderment and fear in his look, and something else as well--alertness, intensity, and yearning. His dark eyes, racing back and forth, were not simply scanning the room, they were searching.”

Surprised that Ildefonso was sane at all, Schaller decided she “must walk outside of language” to establish communication with him: Perhaps then she could attempt to bring him into “the universe of humanity . . . the communion of minds” that language, more than anything else, makes possible.

The first part of “A Man Without Words” is the record of her initial frustrations and crucial breakthrough, the moment of Ildefonso’s “emancipation,” which arrived when he finally understood the link between a cat and the symbols for it, both signed and written: “He broke through. He understood. He had forded the same river Helen Keller did at the water pump when she suddenly connected the water rushing over her hand with the word spelled onto it. Yes, w-a-t-e-r and c-a-t mean something. And the cat-meaning in one head can join the cat-meaning in another’s head just by tossing out a cat .” From then on, Schaller struggled to get Ildefonso to move beyond names, toward verbs and finally grammar.

Ildefonso’s story is instructive and moving, so plainly so that one wishes Schaller wouldn’t keep looking for every possible way to overwrite it. “I began to worry about my sanity,” she says. And: “Riding home on the number 3 bus, everything seemed unreal.”

There is a formulaic melodrama to her account that makes it seem less a book of nonfiction than a treatment for a TV movie-of-the-week. Chapter closings tend to read like cues for a commercial (“I left, once again wondering if I could return on Monday, if Ildefonso would return”), and despite her assertion that Ildefonso is “the hero of this book,” there is a kind of self-aggrandizement in the way our heroine pursues her mission through waterfalls of rhetorical questions: “What had I done? Had I brought Ildefonso to the edge of language where he had a view of his tragedy, a knowledge of his disease, but no hope of relief or a cure?”

There is nothing wrong with imparting knowledge in the form of first-person adventure; biographers and scientists often enliven their findings with tales of how they made them. But Schaller’s proportions are seriously skewed, and too often she is making rhetoric when she should be writing narrative: “I knew I had to enter his cell, sit on the floor with him, and, from his point of view, try to see where the door to language opened. Only then could I point him in the right direction.”

There are also places where a reader is simply left confused: “Can anyone truly imagine deafness?” Schaller asks. “We can close our eyes and sympathize with the blind, but we cannot close our ears.” Well, actually we can.

When Schaller and Ildefonso argue over who should pay for a burrito, he is insistent: “ ‘No!’ his fingers snapped; ‘God, friend. Burrito buy I.’ ” Schaller infers that his use of the sign for God shows that “He connected God and friend and placed them above burrito buying. His anger was that of a religious instructor. I was properly rebuked for my concern for the material world.” I would suspect that from the signers around him, Ildefonso had recently learned to use “God” as an expression of exasperation, and was putting it before the vocative use of “friend.” I do not know American Sign Language, but I would think that, without more explanations than Schaller gives, anyone reading her account of the burrito-buying is going to find the metaphysics a bit fanciful.

“A Man Without Words” does succeed in making a hearing reader consider facts and phenomena that may never have presented themselves to him. When signers have the habit of forming words with their mouths, deaf people say they have a “hearing accent”; and “Even with language, some deaf people never understand hearing. The idea to a person born deaf that meaning can be carried via sound is ludicrous.” But a reader’s pleasure at having this new knowledge is tempered by irritation at the way Schaller’s rote expressions of political correctness (“How could I explain ethnicity and racism in mime and the vocabulary of a two-year-old?”) seem designed to make a hearing reader of European origin feel doubly oafish.

The last third of “A Man Without Words” is devoted to Schaller’s search for “someone else who had learned language as an adult, or someone who had taught a prelingual adult,” and to a reunion, after years have passed, with an extraordinarily progressed Ildefonso. He now takes her to the “languageless people” that she is seeking--and provides her the chance to be “spellbound,” “mesmerized” and in “awe” on a single page.

On the subjects of deafness and languagelessness, “A Man Without Words” is frequently informative and occasionally stirring, but it is also, too often, annoyingly loud.