AT THE CLOSE of this 100th-anniversary year of the publication of "Huckleberry Finn" we should pause in our celebrations of Mark Twain's genius to consider that he wrote a viciously sentimental and opportunistic book.

Of course, it wasn't "Huckleberry Finn." That novel remains one of the finest litmus tests yet devised for fools, school administrators, purveyors of racial prudery and others inflated by the gas of purest sanctimony.

Huck has caused little trouble that Twain would not be proud of. Certainly, he must have laughed to hear that Louisa May Alcott, author of "Little Women," said in 1885: "If Mr. Clemens cannot think of something better to tell our pure-minded lads and lasses, he had best stop writing for them." Imagine his delight if he'd learned that an administrator at the Mark Twain Intermediate School in Fairfax had said in 1982 that "the book is poison. It is anti-American;" this because it uses the word "nigger."

And how he'd rub his hands before the fires of human folly to know that Huck -- template of unshakeable natural virtue and noble savagery -- continues to be attacked when the real opportunist, the ruthless charmer who craves glory above all things, gets held up as an example for American boyhood.

We are speaking of "Tom Sawyer."

Tom, it might be added, uses the word "nigger" just as Huck does, with none of Huck's compassion for blacks, but nobody complains about it much. Maybe that's because they don't read "Tom Sawyer" any closer than they read "Huckleberry Finn."

"Tom Sawyer" is seen as the ideal boy's book, a pastoral tale about youthful skylarking. Maybe it's seen this way because it's well-larded with sentimentality of the boys-will-be-boys variety that views childhood as Eden (if only the children knew it). And on a more abstract level it can be defended as a satire on the chivalric daydreaming that Twain loathed so in Southerners, and as an attack on the pompous tyranny of churches and schools.

But mostly it is a calculated appeal to our emotions in the form of a story about a charming, magnetic boy -- a boy who, as it happens, is a manipulative, fantasy-ridden opportunist afflicted by what Twain himself calls a "vicious vanity."

If you don't think so, try reading it aloud to small children. You will find yourself asked to explain why the hero of this book -- and model for American boyhood -- lies constantly, runs away from home for days at a time, steals from both townspeople and his family, assaults a boy he's never seen before and leaves him "sobbing," swindles his way to a prize at church and throws a rock through a window for petty revenge.

This is not to condemn youthful exuberance. It's understandable that Tom would be bored in church and late to school; that he lies to his Aunt Polly when she asks if he disobeyed her and went swimming; that he succumbs to the temptation of giving the cat, Peter, a spoonful of the same firebreathing painkiller he's been made to swallow; and that he attacks his half-brother Sid, a horrible little prig of the sort who, come to think of it, would probably grow up to attack books like "Huckleberry Finn."

And this is not to say that Tom is some kind of psychopath; he has a conscience -- Mark Twain's characters tended to drag consciences behind them like balls on chains -- and risks his life telling the truth in order to save Muff Potter from hanging. But he gains glory by it, and whenever glory is at stake, Tom will risk anything, truth or lie. "Glory was sufficient," Twain writes. "He would live for glory."

Maybe this is why Tom has escaped the wrath of the righteous -- because unlike Huck he's so wonderfully 20th century, pure personality, a boy who knows that you sell the sizzle, not the steak, a self-aware lad who nowadays would grow up to stare out at us from the cover of "People" magazine. Judge Thatcher knows a thing or two when he says at the end of the book that Tom will make "a great lawyer or a great soldier someday."

Sure enough, Tom Sawyer is a master of proprieties and social subtleties. He can lecture on the etiquette of being engaged to marry, the vernacular of square-rigged ships, and the obligations of hermits, among other things.

He's also a master psychologist. As his Aunt Polly says, "He 'pears to know just how long he can torment me before I get my dander up, and he knows if he can make out to put me off for a minute or make me laugh, it's all down again and I can't hit him a lick."

He manipulates mass emotion as well in a scheme to persuade the whole town that he, Joe Harper and Huck Finn have been drowned. He actually listens to his Aunt Polly weep for him, then keeps her grieving for days so that he can hear the oratory at his own funeral. Think about it: What if your kid pulled a stunt like that?

Huck Finn wouldn't. Huck would be crippled by simpleminded sympathy and loyalty. Unlike Tom, who takes any glory he can get, be it fame or infamy, Huck finds little joy in the attention of society. Like Tom he finds its rules oppressive, but unlike him he craves not power over it but freedom from it. He doesn't even want his share of the gold that he and Tom find.

"Huckleberry was cordially hated and dreaded by all the mothers of the town, because he was idle and lawless and vulgar and bad." So Tom "played with him every time he got a chance."

No wonder we think Huck is a menace. If power and money can't tempt him, and if he's constantly sickened by society's cruelty and hypocrisy, he's beyond our reach, out of control. He'll be lucky to escape horsewhipping or worse in his life. Tom, meanwhile, has the makings of a splendid politician or corporate executive.

But Huck has the one thing that charisma-vendors so often seem to lack -- authenticity. This is why Tom can't stay away from him. Of course, Tom can't resist trying to convert him to his world of fame and civilization. He pleads with Huck at the end of the book: "If you'll try this thing just a while longer you'll come to like it."

This is in the spirit of any number of latter-day Tom-Sawyer-like hotshots who comb the world for unspoiled retreats to spend their money on, Edens of lost authenticity. "Look!" they say at last. "A fishing village with real fishermen!" Then they break ground for the French restaurant.

Tom can't bribe the incorruptible Huck, though he might be able to go bail for him someday. Huck is a loser, Tom a winner. It's how the game is played. And it's why Tom is the model for our children, and Huck a dangerous example to warn them against.