In case you'd been wondering what to take to the beach this summer, the literary marketplace has some helpful hints for you. Turn to the back of any dust jacket and you'll be assaulted by a barrage of blurbs, each of them designed to persuade you to come forth with $16.95 plus tax. A few samples from books now making their way into the stores:

*"'Private Lives' should be public knowledge! Benita Eisler has done it again: given us a revealing look at ourselves while enjoying our sense of fun. She's the best" -- Rita Mae Brown.

*"A masterly combination of truth and fiction by a man who saw it at first hand. Ehrlichman's insight into the intrigue between Peking and Washington, D.C., makes for a gripping read" -- Clive Cussler.

*"Thrillers don't come better than this . . . A marvelous read" -- Jack Higgins.

*" 'The Second Creation' is an absolutely marvelous book. No one who cares about science should miss reading it" -- Timothy Ferris.

*" 'Dead Air' marks Mike Lupica's emergence as more, much more than the fine sports columnist he has always been. He shines through as an extraordinary writer of vast distinction with style, pace, tension, story line, and the power to combine these qualities in an encompassing way that grips you on every page. You'll love this book -- and that's telling it like it is" -- Howard Cosell.

Makes you want to rush right out and buy, doesn't it? "The best," "a masterly combination . . . a gripping read," "a marvelous read," "absolutely marvelous," "an extraordinary writer of vast distinction" -- that's telling it as it is, all right. As it is, that is to say, in the wonderful world of blurbs, where hyperbole reigns supreme and caveat emptor is the order of the day. The blurbs quoted above are a random and entirely arbitrary sample, but they are eminently representative of the blather with which book jackets, and book advertisements, are adorned. All of them make for lively if cliche'd copy, but none of them contains a clue to the question that a seasoned blurbologist automatically asks: Why did he write that blurb, and does he mean a single word of it?

It's a fair question, for the motives behind blurbs are often complex and suspect. In no other business are advance comments so promiscuously solicited and so promiscuously given as they are in book publishing, and it is common knowledge within publishing that a wholly disinterested blurb is approximately as rare as a day in June. People give blurbs because they are friends of the author, because they owe the author a favor, because they hope to exact a favor from the author, because the author's publisher happens to be theirs as well, because they want to be in on the launching of a career, because they like to see their names in lights -- but rarely, oh so rarely, because they think that what we have here is a marvelous, I mean to tell you absolutely marvelous, book.

The best counsel, therefore, is to take blurbs as lightly -- and cynically -- as they are usually given. They bear no relationship to quotations from reviews, and are not to be confused with them. The last thing the innocent reader should believe is that a blurb, like a review, represents objective opinion; even when unimpeachably honorable people are involved in the blurbing, ulterior motives are at work that have relatively little to do with the actual merits of the book being blurbed -- although sometimes, to be sure, it is difficult to figure out what those motives might be.

A current case in point is "The Good Mother," a novel by Sue Miller that is interesting thematically but inept as a work of fiction. Yet it comes adorned with a blurb by John Fowles, a gentleman of much distinction who is no regular on the blurb circuit, that reads: "A very gifted first novel, outstanding for its subtle accuracy and honesty. I have not read a better for many years." A better what? is the logical response, for the novel scarcely lives up to Fowles' high, and rare, praise. Why did he do it?

Ditto for a truly awful novel by Stephen Vizinczey, "An Innocent Millionaire," which for reasons known only to the parties involved drew from the reclusive and reticent Graham Greene this comment: "Bravo! This long, serious, beautifully organized novel is the more remarkable for containing the best funny scene I have read since Evelyn Waugh" -- a scene I dutifully searched for but never found. And what on earth possessed Robert Penn Warren, another eminence rarely seen in Blurb City, to call "Blue Highways," by William Least Heat Moon, "A masterpiece . . . a magnificent and unique tour"?

These are mystery blurbs: They come down from great heights, bear no evident relationship to the books being blurbed, and throw veteran blurbologists -- not to mention innocent readers -- into utter confusion. But they are exceptions to the rule. Most blurbs are as easy to decipher as a Dick-and-Jane primer. The macho New York journalists always blurb each other; the TV people polish each other's apples, even if they don't write their own books (or blurbs?), and political types often chime in with words of praise for talk show hosts and news anchors; the sports crowd takes care of its members, as does the good-ol'-boy network down South; minor literary novelists take very good care of each other, and sometimes even a Great Man, a personage renowned in all the writing departments, stoops to lend them a helping hand.

"You blurb me, I'll blurb you" -- Shakespeare probably said it to Bacon, Balzac to Hugo, Chekhov to Tolstoy. Writers have been scratching each other's backs for centuries, though the exact origins of blurbing are lost to history and its actual effects on sales and reputations are equally mysterious. There is ample reason to believe that a sheaf of laudatory blurbs does wonders for a writer's always fragile ego, but does it really bring people into the bookstores? In small, specialized markets, perhaps blurbs work; a kind word on the dust jacket by C. Vann Woodward, for example, is a sign to historians of the South that a book is worth a look. But in the broader trade market, blurbs are so commonplace -- and sound so much alike -- that most of them probably go unnoticed by all except the parties immediately involved.

But those, of course, are the parties for whom they are really written. They're written because authors love to get them, publishers love to print them and some people just plain love to give them. They're compulsive blurbers whose names appear so often in the advertisements and dust jackets that you want to shout, "Stop that man before he blurbs again!" But like true junkies, they just blurb on; the best advice is to regard them as harmless nuisances, and pay no attention.