THE MUSEUM OF THE MIND : Oh, do not ask, “What is it?” Let us go and make our visit : MR. WILSON’S CABINET OF WONDER, <i> By Lawrence Weschler (Pantheon: $21; 176 pp.)</i>

It was, I think, a gray and rainy day in Cleveland when I saw my first museum, and of the museum itself I can recall almost nothing. What I do remember is a man’s head, maybe five feet high, constructed of wood, and painted a sickening flesh tone. It had a mouth which, if you pushed a button, would lurch open to a sneeze (for this was a Health Museum) and send brightly colored Ping-Pong ball-like germs out to a distance of about 20 feet. It was a sight, even to a 5-year-old with a runny nose, that made it clear absolutely none of this was really necessary.

Thinking about it now, I would be amazed if this memory is correct, but I still find the head far more wonderful than what it was supposed to demonstrate. Who spent his time making such a contraption anyway, and how did the head of my memory wind up more real than the one of fact? Did he who made the see-through plastic sexless human whose parts lit up make thee?

Believe it or not, these and other questions are addressed, if not answered, in Lawrence Weschler’s miraculous account of the Museum of Jurassic Technology, “Mr. Wilson’s Cabinet of Wonder.” The title, though possibly cumbersome, echoes the language of both magic and early museums of natural curiosities, as well as does honor to the MJT’s sole founder, David Wilson. The book’s subtitle, “A Natural History of Amazement,” also introduces the book’s broader theme, the changing definition of the unusual, and how we choose to treat it.

On both subjects, the book is a joy. Weschler’s first four pages, an account that combines spore-eating ants, a theory of memory (that no such thing exists) and a Romanian-American opera singer in South America, had me shaking with pleasure. After completing the book, I’m not surprised. Such a symptom is, according to the author, itself a classic reaction to exposure to wonder, “ . . . something like the ‘startle reflex’ in infants: eyes widened, arms outstretched, breathing stilled, the whole body momentarily convulsed.”

Then, after explaining how all these elements happened to be together (“Mr. Wilson’s Cabinet” reads like part Borges, part Raymond Roussel), with the resulting deflation of excitement, Weschler goes on to present another, equally mysterious conjunction, and then to explain it. The book’s strategy, in a way, is to keep repeating that process, like one of those video games where the successful completion of one task just leads you to another, even more bewildering.

Lest the reader be too confused at this point, let me say that the book’s inspiration, if not sole subject, The Museum of Jurassic Technology, actually exists, and is located in the 9300 block of Venice Blvd., in Culver City. Jurassic technology itself, given that the Jurassic period ended about 135 million years ago, seems, well . . . a combination of measurement, luck, and . . . memory (whatever that is). Weschler himself avoids any such crass definition, but if you are inclined to scoff or dismiss such a concept as a mere joke, it’s not a bad thing to recall certain notable criminal trials, where the outcome seems to depend precisely on such a combination of the scientific, coincidence and that fiction we choose to call memory.

The actual museum rests, as the definition of Jurassic technology itself, on many planes at once. First, it’s a collection of objects that amaze, that set the heart trembling. Next is an attempt to describe those objects in as precise a way as possible, and finally a theory to explain the relationships of those objects.

That the MJT exists in Los Angeles, a locale that is itself the most powerful generator of cinematic fiction the world has ever known, is probably not a coincidence. Its founder, David Wilson, began his own explorations of the world as a filmmaker. The museum’s collection, at “the very intersection of the premodern and the postmodern,” shimmers, to use Weschler’s word, like the projection of light particles through film onto a screen.

So the first part of the book (most of which appeared in Harpers last year) focuses, in a sort of shimmery way, on the MJT itself and its founder. The second half takes things a bit further. It examines the world behind them both--history--and provides, in a way, yet another explanation, beginning with the discovery of North America (and especially California), culminating in the museomania of the 17th and 18th centuries.

Thus, as we read this book, our amazement evaporates and is replaced by a knowledge which itself becomes the generator of new amazement. “Mr. Wilson’s Cabinet of Wonder,” therefore, turns out to be about a subject even more pleasurable than wonder, and that is the tension between knowledge and mystery. The more we know, the less mysterious (and therefore dull) the world seems, and yet, the more we know, the more mysterious things become. (On this subject, it’s appropriate to mention that this book comes with 35 pages of end notes, each of which simultaneously elucidates and obfuscates its referent. They range in subject from the Weschler’s daughter’s belief in Santa Claus to examples of horns growing out of the human skull.)

One of our finest investigative essayists, Weschler is always alert, attentive, and never overbearing. As in his near-legendary study of the artist Robert Irwin, “Seeing Is Forgetting the Name of the Thing One Sees,” he allows the reader to accompany him on his exploration of the subject, rather than force his interpretations onto us. Weschler invites us to look along with him, to ask our own questions and then to draw our own conclusions.

“The most beautiful experience we can have” as Einstein says, “is the mysterious. It is the fundamental emotion which stands at the cradle of true art and science. Whoever does not know it can no longer wonder, no longer marvel, is as good as dead, and his eyes are dimmed.” Who hasn’t thrilled momentarily at the headline of a supermarket tabloid even as we laugh at its improbability? And if World War II bombers were found on the moon, if both Jesus and the devil scattered their calling cards on tortillas, bathroom walls and thunderheads, what a world that would be!

So where, besides at the site of Museum of Jurassic Technology, is the actual intersection of fact and wonder? That may be more important question than many of us care to admit. I remember, a few years ago, a survey in which non-artists were asked to rank the importance of talent, hard work and luck, in achieving success. They did so in that order. The same question, asked of successful artists, put luck--sheer coincidence--on top. It is magic, in the words of Octavio Paz, which “affirms the fraternity of all things and creatures. . . . .”

Do such matters sound like fun? I hope so, because they are, and “Mr. Wilson’s Cabinet of Wonder” not only provoked my own muddle-headed amazement, but was the most charmingly provocative read I’ve had in a long time. With that other famous intersection of mystery, science (astronomy), and fiction (I mean Christmas, of course) soon approaching, this lovely, eccentric book seems to me the perfect gift.