E.T. is a botanist, as you might guess if you pay close attention in the opening frames of the picture that bears his name. He is very old--in fact, he has been visiting Earth periodically to sample its vegetation since things began growing on this planet--but you could hardly know that unless someone told you, as William Kotzwinkle (author of "Doctor Rat," "Elephant Bangs Train," "Swimmer in the Secret Sea" and a half-dozen other books) does at the beginning of his novel.

Or rather his novelization. In the beginning was the script, and the script begat the film, and the mating of film and script begat the novel and will probably beget E.T. stuffed dolls and windup toys and comic books and other spinoffs--how about a family sitcom series for television? If the process sounds a bit incestuous, that is because it is a bit incestuous. But "E.T." the novel has certain values beyond those related to cash flow, as does "E.T." the film, and it is worth examining those values.

In its simplest terms, the novel tells you the story of an aged and very wise being from another world who is stranded on Earth, befriended by some terrestrial children and nourished on M&M candies, Oreo cookies, Milky Ways, Pepperidge Farm pastries and similar delicacies, which he finds not only the hautest of haute cuisine but spectacularly nourishing. The kids--particularly young Elliott, who initiates the contact--hide E.T. in a closet along with a lot of other stuffed toys. As in the movie, their mother sees him there without noticing that he is any different from all the other monsters lined up neatly in an otherwise untidy room. But in the novel we have been informed that E.T. has begun to love her, although as the time-honored phrase says, they come from different worlds. He wonders whether--rather than return to his own society--he might not be "happier in the closet, near Mary, for the rest of his days." But the fact that she did not notice him among the stuffed toys tinges his thoughts with melancholy. "How could she love him," he wonders, "when he was no more to her than Kermit the Frog?"

Before making his contact with the humans, E.T. has frequent, telepathic conversations with earthly vegetation, which he has known intimately for millions of years. He also establishes a kind of communication and mutual respect with Harvey, the family dog, though the conversation is not intellectually stimulating. He thinks deep thoughts about the game of Dungeons and Dragons, which the Earth children are playing the first time he sees them, and about the story of Peter Pan, which he hears from an adjoining room. Before going on his memorable drinking bout, he investigates the contents of a beer can with chemical if not biological precision: "His tongue ran a quick analysis of the components of the beverage: malted barley, hops, adjunct of rice and corn. Should be perfectly harmless."

None of these interesting details is as explicitly presented on the screen as they are in the book. Quite simply, the difference between the two media is that the book tells you a story, but the picture is something that happens to you. The picture does not take time to stop and explain; it puts you in a situation and lets you guess about the background, monitor the overtones and perceive the well-hidden clues as best you can. The two experiences are fairly similar in general outline but quite different in small, specific details of perceived content. Each has its own validity, but in this case at least the film has a stronger impact. No description in the book, for example, has the emotional effect of the farewell scene at the movie's end when Elliott hugs the strange creature. On the other hand, the picture has conceptual lacks, even though they may not bother you while you are sitting in the darkened theater wondering what will happen next.

Actually, a film like this is a sort of Rorschach test, a series of visual images that each viewer fills with meaning according to individual tastes and backgrounds, and the novel gives us one set of reactions. Kotzwinkle takes the liberty of changing the plot in small details, but the variations are not serious. For example, he has Elliott use M&Ms rather than Reese's Pieces as the bait to lure E.T. into his home--perhaps simply in order to present one close-up that triggers a reaction conditioned by years of exposure to advertising: "The ancient wanderer held out his hand and opened it. Within the huge scaly palm was his last M&M, melting." Perhaps, against all biological probability, his quasi-reptilian species has hands warmer and more moist than the human hands in which these candies refuse to melt?

Kotzwinkle's work is excellent as film novelizations go but not comparable to the great novels of science fiction. It is drawn from a source inherently too weak in conceptual content, and it is handicapped by the need to replicate the main episodes in the film, some of which were conceived for another medium. On film, for example, the chase scene with police cars pursuing kids on bicycles has an impact and an inner logic that it simply lacks on the printed page, chiefly because Steven Spielberg can show you while Kotzwinkle has to tell you.

Reading the book will give considerable depth and context to the experience of the film--better afterward than before, so that the suspense can remain unspoiled. In no way is it a substitute for the film--but there seems to be little danger that many people will read the book without seeing the movie.