The Grinch Behind the Cat in the Hat : DR. SEUSS & MR. GEISEL: A Biography, <i> By Judith and Neil Morgan (Random House: $25; 352 pp.) </i>

I don’t remember the first words I spoke as a child, but it wasn’t long before my lexicon included standards such as house, tree, boat and oobleck . Oobleck, if you don’t remember, was the gooey green stuff that came plotzing down from the sky and stuck to virtually everything. It was a fantastic, apocalyptic phenomenon, and it occurred in Dr. Seuss’ sixth or seventh book. By that time, he had already introduced me to an egg-hatching elephant and a kid who grew hats out of his head. Yet to come were creatures called Sneetches, places called Fotta-fa Zee, Truffula trees, miff-muffered moof--a zany new vocabulary.

I never met Dr. Seuss but I always imagined he would be very much like the creatures in his bold, rackety picture books; a swaggering Cat in the Hat, or a Sylvester McMonkey McBean, full of bravado and mischief. Even his name, Seuss, like Zeus, conjured up a grand, otherworldly figure.

In fact, as I was to learn much later, Seuss was the pen name of Theodor Geisel, a rather shy fellow who spent most of his time holed up in his tower studio out West in La Jolla. I was told that he dreaded large crowds, small children and television talk-show hosts and throughout his life attempted to avoid them all.

The facts about this quirky genius became only more apparent to me reading Judith and Neil Morgan’s engaging new biography “Dr. Seuss & Mr. Geisel.” It’s the story, you might have guessed, of two personalities: the author, whose irrepressibly playful nature enabled him to captivate the minds of children (and incidentally make millions of dollars), and the man who never felt entirely comfortable in the role of an adult because, as his first wife claimed, “his mind never grew up.”

The man, Mr. Geisel, is shown to be an affable social misfit, waggish and animated in private life, awkward and introverted in public. Wealth and fame never changed him. Even when his books had made him a fortune, he stubbornly refused to switch to an electric typewriter, calling it “too sophisticated.” His first wife joked that when he wasn’t consumed with his work his “only two extravagances (were) ‘cigarettes and rocks.’ ” He chain-smoked the cigarettes. The rocks he arranged into paths in his desert garden. Extravagant indeed!

Throughout his life, Ted Geisel attracted women who instinctively sheltered him from the real world. His first wife, Helen Palmer, acted as his spokeswoman, editor and critic and was ever ready to pull him out of some entanglement. She took care of financial matters, which bored him, and arranged dinner parties, which he loathed. She did all the shopping. Well, of course: Ted rarely carried a wallet! When publishers suggested book tours or interviews, only Helen could coax the reticent author down from his tower.

The Ted-and-Helen affair was a curious, claustrophobic, 40-year saga, which ended suddenly with her suicide in 1967. Almost a year later, in an odd set of circumstances, Geisel married Audrey Dimond. As he explained to a colleague: “My best friend is being divorced and I’m going to Reno to comfort his wife.”

Ironically, just as Geisel’s first marriage was disintegrating, Seuss’ fame was soaring. It was 1957. He’d just been named president of the imminently lucrative Beginner Books. “The Grinch Who Stole Christmas” was about to be published to great acclaim. But the year’s great moment was the sensational arrival of “The Cat in the Hat.”

So, what about “The Cat in the Hat”? What could have spawned this colossus of kid’s books? As the story goes, a Houghton Mifflin editor, fed up with “Dick, Jane and Spot,” encouraged Seuss to write a book for a slightly younger audience using a vocabulary of no more than 225 words. After perusing the editor’s word list innumerable times with no luck (“There are no adjectives!”), he gave it one more look, determined to use the first two words that rhymed as his title. (Luckily for Seuss, they weren’t dog and log .) A few years later, his publisher, Bennett Cerf, dared the doctor to limit his vocabulary to 50 words. Seuss, of course, won the bet. The result was the outrageous “Green Eggs and Ham.” God only knows what he might have done with 10 words!

When he was in his 70s, Geisel attempted to write an autobiography but soon tired of the idea: “Who could possibly care about these details?” The answer is, thankfully: Judith and Neil Morgan. Their book is neatly woven with little-known facts, obscure Seuss doggerel not intended for children and such tragic articles as Helen Palmer’s suicide note. There are examples of Seuss books in progress, images of Geisel struggling over the last page of “Grinch” and accounts of rare Seuss blunders, such as the wacky 1939 World’s Fair contraption, the Infantograph, which was intended to merge the photo likenesses of married couples and produce a picture of their future child.

How are you on your “Seussiana”? Did you know that the author Theo Le Sieg (“I Can Write! A Book by Me, Myself,” “Maybe You Should Fly a Jet! Maybe You Should Be a Vet,” among many other titles), whose name backward spells Geisel, was Seuss? Or that Seuss, through an Art Buchwald column, may have contributed to Richard Nixon’s resignation?

Occasionally, the Morgans’ data verges on the banal, as when they describe the day-to-day activities of a Seuss vacation trip or reveal what celebrity he stood next to at a party. But then, for a “Seussophile,” it’s all gravy.

The title of the biography suggests an eerie correspondence to “Dr. Jekyll and Mr. Hyde.” Did Seuss, alone in his tower studio, uncontrollably metamorphose into a Grinch, a Wumbus, a Sneedle or Humpf-Humpf-a-Dumpfer? On this subject the Morgans are unusually silent. Their biography is more about life and career than an examination of Seuss’ mysterious creative process. On occasion they do cross the line. I was amused (as was Seuss) with critic Selma G. Lanes’ comparison of the “unbearable tension” and final release in his books as “not so far removed from orgasm.” Seuss as a substitute for sex? Maybe it’s time to reread “On Beyond Zebra.”