My Baby Wrote Me a Letter : THE GOLDEN MEAN: In Which the Extraordinary Correspondence of Griffin and Sabine Concludes, <i> By Nick Bantock (Chronicle Books: $17.95)</i>

Anyone who has ardently awaited the mail delivery, hoping for a letter from him or her amid the morass of circulars and bills, anyone who has ever snuck a surreptitious look at another person’s private correspondence (we know who we are), will respond to the voluptuousness of Nick Bantock’s Griffin & Sabine trilogy. The final volume, “The Golden Mean,” is just out. The mystery that gave the series some narrative intrigue is solved--sort of.

Like its best-selling predecessors, “Griffin & Sabine” and “Sabine’s Notebook,” “The Golden Mean” is a lavish picture book for adults, contrived as an exchange of letters and postcards between a youngish man and woman who seem to be soul-mates in the Platonic sense, each seeking the other half of himself that makes for completeness. Though these two have never met face to face, they grow increasingly, urgently intimate as their epistolary relationship progresses. “How strange to have a paper love,” Griffin remarks. Since they are both visual artists--consciously performing for each other’s temptation and delight--their communications are not restricted to words. They flower as extravagant visual images: rich in color, detailed adornment and inventive (even bizarre) juxtapositions.

The postcard messages are shown from both sides--a reminder of the unfortunate but common attitude toward such mail as being prey to anyone’s scrutiny, not the private property of the addressee. As in real life, the letters are more secret. Consisting of an open envelope from which the reader extracts the page, they have a tantalizing effect, bringing the sense of touch and muscle memory into the picture and arousing associations with a whole history of letter-openings in the reader’s own life. Strangely, the effect remains potent even a second and third time around.

As for Griffin and Sabine, with whom we become acquainted so illicitly--who and what are they? Aesthetic and erotic pen pals, perhaps, in a mystical world created either by their own imagination or by a supernatural time-and-space warp. Griffin Moss is an illustrator living in quiet solitude in London. From the art Bantock assigns to him we can assume he is admiringly acquainted with the strategies of Max Ernst, Joseph Cornell and their ilk. The geographical opposite of her urban correspondent, Sabine Strohem is a child of nature, a native of the undespoiled Sicmon Islands of the South Pacific. Like him, she’s a commercial artist. (Both ply their trade as if it were fine art, an attitude that endears them to us.) Sabine designs the postage stamps of her tropical paradise and embellishes her correspondence with whimsical variations on God’s creatures or analytic pencil sketches. Her models might be Miro and the Da Vinci of the notebooks, though neither accounts for her generous--and ingenuous--dispensing of phallic symbols. She writes a graceful italic hand in burgundy ink; Griffin’s script is block capitals in sober navy or black. Occasionally he types, with just the right, charming amount of human error. A fax machine--or even a telephone--would annihilate their relationship.

Sabine, apparently, has been haunted since puberty by visions of Griffin’s art. When she finally comes upon a concrete piece of it, attributed, in a magazine article, she naturally gets in touch with him. Griffin, appropriately pleased and unnerved, responds in kind. They write. And write. We, innocent voyeurs, get to examine, savor and wonder over each piece of mail. The pair attempts to meet, Sabine journeying to London and living in Griffin’s flat after he has fled in terror from the approaching encounter. Having cast Sabine in the role of muse, he begins to believe she’s a ghost, haunting him, possessing him, threatening to consume him--or that he’s going mad. And so it goes, provoking further pilgrimages, physical and spiritual, until, finding a balanced midpoint--the golden mean, a rule of harmonic proportion that governs classical art--the two come together. This being today, nothing is said about marriage; the requisite “happily-ever-after” is implied by a baby. Actually, nothing much is specific at this final point; once Griffin and his Sabine are united, they seem to disappear off the face of the earth.

In a way, the story, which we see primarily through Griffin’s eyes, is the ultimate in Romantic wishful thinking: A man is shadowed by a woman who fills him with an amorphous fear. At the same time he ardently desires her because she “knows” him fully (indeed, knows the most revealing and self-expressive part of him: his art) without his even having to connect with her. She simply intuits him. He is the seeker, but that role is expressed through yearning, flight and journeys to faraway places to “find himself”; she--gentle and lovely, filled with earth-wisdom no doubt infused into her by her foster mother, a midwife--is the practical pursuer. That gnashing of teeth you hear is the feminists’.

The story has other drawbacks, such as the belated appearance of an unconvincing villain, the unsatisfying obliqueness of the long-awaited resolution and the banal assignment of gender-linked qualities according to New Age pop-philosophy, the male representing logic (and its limits); the female, instinct (and its miracles).

The real enticement of these books lies in their physicality. The genre is now called “interactive novel,” which makes one want to counter with a surly, dismissive, “Yeah, pop-up books for grown-up highbrows.” The truth lies somewhere in between, and Bantock manages with fairly irresistible allure to provide food for the eye and to recreate the situation in which the arrival of a letter is an important event--in terms of the news it delivers and the feelings it confesses or implies. And yet something essential is missing; the considerable pleasure a susceptible reader (we know who we are) may take in the trilogy remains a superficial one.

Bantock, a prolific illustrator of book jackets before he hit pay dirt, knows what sells, and his books reveal that canniness. Both the art and the text are exotic (mildly, though, not daringly), sensuous (the pictures in a decorative way, the text rather too tastefully so), and fascinating in that they keep you wanting to know more than you’re allowed to. Neither element, however, probes beneath the surface; neither gives you an enlarged sense of life, which is the ultimate gift of great literature and great painting.

Oddly enough, the author-artist has gone a little further in his less ambitious pop-up books. In these cheerfully unassuming, fit-in-the-palm constructions, Bantock gives traditional rhymes and a couple by Lewis Carroll a latter-day psychological twist by suggesting that all the characters in the narrator’s tale are figments of his imagination--specifically, projections of himself. Now there’s an idea, the proposition that the other people in your world are merely yourself in a false beard, tricked out in costume--that is, yourself in disguise. And what’s more, it’s being offered to children, who are still blessedly and dangerously shaky on distinguishing between fantasy and reality.

But I haven’t mentioned the aftershock--and perhaps the best aspect--of the Griffin & Sabine books: They ignite the reader’s latent hands-on artistry. They make you want to own a fountain pen again, to experiment with different inks until you find the one that suits your temperament, to write letters instead of phoning long distance, to steep yourself in color and texture, to compose collages of objects with strange and profound intimations, to be creative and indirect instead of brutally mechanical and straightforward, even to seek yourself and that significant other through uncharted realms--for isn’t love, too, an act of the imagination?