Not being one to take a compliment lying down, Graham Greene attended a festival in his honor last week and pronounced the affair to be in substantial measure hogwash. As usual, Greene was right.

The occasion was the opening, at the National Film Theater in London, of a retrospective of films adapted from Greene's novels and stories. Twenty-three are to be shown, only two of which -- "The Third Man" and "The Fallen Idol" -- Greene regards as satisfactory. Eight of them, in fact, Greene dislikes so intensely that he described the retrospective as "an ambiguous festival" and told the audience: "You're celebrating with what I consider eight very bad films," among them "The Man Within," which he called "shockingly bad," and "The Comedians," which rated as "a disaster."

Attempting an explanation for this sorry record, Greene said: "Very few good films have been made out of my books, so they can't be that cinematic." This judgment is perhaps less astute than his judgment of the films themselves. In certain respects Greene's fiction is intensely cinematic, no doubt reflecting the lessons learned during many years as a film critic and during a few stints of his own at screenwriting; among these cinematic qualities are his books' vivid sense of physical place, their crisply convincing dialogue and their equally crisp plotting.

Greene came rather closer to the mark when, in commenting on the successful adaptations of "The Third Man" and "The Fallen Idol," he said: "A short story makes a much better film than a novel. A novel is too long, has too much material, and there have to be too many compromises." By "much better film" he apparently means a film that is more faithful to the original material; as he says, in a short story there's less material to which to be faithful, while a novel positively bulges with people, incidents and themes that moviemakers eagerly eliminate, compromise and/or distort.

Consider, by way of recent and instructive example, the film adaptation of Larry McMurtry's novel "Terms of Endearment." Seen purely as a movie, devoid of any previous life or history, it is an excellent piece of work. But seen as a dramatization of McMurtry's novel -- the best of the many novels he has written -- it is something else again. In order to meet the demands of the screen, which are almost entirely different from the demands of the novel, "Terms of Endearment" was telescoped to a shadow of its former self. The character of the former astronaut, for example, played so brilliantly by Jack Nicholson, does not exist in the novel; he is both an original and a composite of several of Aurora Greenway's suitors, there being too many of these in the novel to depict in a two-hour movie.

McMurtry has publicly expressed his admiration for the film generally and the Nicholson character particularly; this admiration certainly seems to be genuine. But McMurtry has an ability, rare among writers, to see a film as something quite separate from the novel that spawned it. This may be a matter of luck -- from "Hud" (originally "Horseman, Pass By") to "The Last Picture Show" to "Terms of Endearment," his novels have received handsome film adaptations -- but it is also one of clear-eyed realism; movies and books occupy completely separate worlds, McMurtry knows, and never the twain shall meet.

This is a truth that too few authors (or, for that matter, readers) appreciate. When the movies come knocking, authors positively shudder with ecstasy; ahead of them, they confidently believe, lie nothing except fame, a huge audience and uncountable riches. From time to time these rewards actually do come to them, but invariably it is at a high price: the distortion, sometimes beyond recognition, of their work. Their reaction to this is usually different from that of Greene, who looks at the adaptations of his books and pronounces them, quite simply, bad movies; rather, these authors, unable to separate the movie from the book, feel a genuine sense of betrayal, a sense that their work has been terminally corrupted.

What they fail to understand is that a moviemaker wants, at most, only two things from a book. The first, the sine qua non, is a story -- or, as the movie folk are given to saying, a "concept." For a new variation on boy meets girl -- "Sophie's Choice," to name one, or "The Natural" -- the movies will pay handsomely. They'll pay even more if the story comes equipped with the second selling point: a following. A book by a well-known author, and/or one that has spent several months on the best-seller lists, becomes, in effect, a presold movie; a huge audience is out there waiting for the movie version, which makes the moviemaker's advertising and promotion far easier.

But a following is strictly a bonus, albeit a most welcome one. It's the story that counts, and from the book itself this is all the moviemaker wants. You can hardly recognize Philip Roth's "Goodbye, Columbus" in the movie, but the story is there; that's what Hollywood bought it for. The relationship between William Faulkner's "The Sound and the Fury" and the movie version of it is almost impossible to discern, except, of course for the story, which -- along with the notoriety Faulkner had acquired through "Sanctuary" -- was all that Hollywood wanted.

The movies don't want a writer's images, his themes, his dialogue, though occasionally they use the last because as long as they've paid for it, why not? They aren't even particularly interested in his characters, since as McMurtry well knows they're going to invent their own anyway. They merely want a property, and once they have acquired it they feel free -- as in fact they are, unless contractual provisions stipulate otherwise -- to do anything they want with it. This includes, as Greene well knows, the freedom to make a bad movie out of a good book.

If anything, a case can be made that the movies are incapable of turning a very good book into even a passably good movie. The library shelves are full of superior books from which awful movies were made, and one indisputably great book has spawned more bad movies than it is possible to count. That book -- and this certainly should comfort Graham Greene -- is the Bible.