THE SAME visionary impulse that produced Steven Spielberg's wonderstruck UFO movie, "Close Encounters of the Third Kind," has now inspired a fresh, delightful variation on the theme: "E.T." Both films are propelled by the need to reach Up There or Out There, to verify the existence of sentient beings beyond our earthly habitat and confirm a spiritual rapport across the cosmos. Spielberg does it masterfully.

Opening Friday at 13 area theaters, including an engagement in 70mm and six-track Dolby Stereo at the K-B Cinema, "E.T" is a science-fiction comedy-fantasy-suspense thriller which traces the development of a profound emotional bond between an ugly-beautiful little creature from outer space and a valiant, resourceful kid from the American suburbs.

A straggler, the creature is inadvertently left behind by a spaceship which has landed under cover of darkness in a dense forest, where several diminutive silhouettes can be seen gathering examples of the flora. Facing apprehension by a shadowy group of human hunters who have witnessed the sudden departure of the ship and detected his presence, the abandoned, terrified alien beats a desperate retreat through the woods, struggling to elude the beams of darting, pursuing searchlights. The thick, protective underbrush suddenly ends and the fugitive confronts the outskirts of civilization--a suburban community nestled in the foothills.

The creature seeks concealment in the back yard shed of a house that borders on a cornfield--a setting bathed in hazy, dreamily beautiful moonlight--but he's a little noisy. He attracts the curiosity of one of the residents, a 10-year-old boy named Elliott, the middle sibling in a family of five recently reduced to four. (The parents have separated, we discover, and the father is conspicuously missing. According to rumor, he's somewhere in Mexico with his girlfriend.) Investigating a strange rattling in the shed, Elliott cautiously stands outside and tosses his softball through the open door. An instant later the ball is tossed right back at him by an unseen hand.

Despite this unnerving experience, Elliott proves to be an ingenious investigator. Snooping around the property the following night, he meets his quarry face to face and the suddenness of the encounter scares them in opposite directions. However, Elliott knows that this "goblin" is not a figment of his imagination. He hits on an approach that works like a charm: a friendly, irresistible offering of M&Ms. Reassured, the creature reciprocates with an offering of his own and then enters the sanctuary of Elliott's bedroom, scooping up a trail of candies with two long, dexterous digits. And so begins one of the funniest, sweetest love stories in movie history.

E.T., short for "extra-terrestrial," is the nickname given by Elliott (Henry Smith, a juvenile actor who combines winning naturalness with an amazing expressive range) to his squat, inquisitive, exotic guest. The names of child and creature are intended to suggest affinities. Spielberg shows the process that leads from these tentative opening gestures of friendship to an abiding, supernatural attachment: E.T. reveals miraculous powers and his liking for Elliott imposes remarkable forms of closeness, like telepathy and interlocked metabolisms.

"E.T." is essentially a spiritual autobiography, a portrait of the filmmaker as a typical suburban kid set apart by an uncommonly fervent, mystical imagination. It comes out disarmingly funny, spontaneous, bighearted. "I wanted E.T. to become a kind of conscience and companion to kids growing up in the '80s," Spielberg said in a recent interview. "In the '50s I had Jiminy Cricket and Winnie-the-Pooh as imaginary sidekicks and preceptors. They were creatures who outlived their original contexts and I hope the same thing happens with E.T."

Elliott and E.T. may have begun as alter egos of the filmmaker, but they emerge as autonomous, fully imagined characters. The chronicle of their friendship is deftly contrived to generate a giddy succession of humorous episodes, sustain a melodramatic plot and inspire rich sentimental gratification.

The humor revolves around culture shock. E.T. finds it necessary to adapt to Elliott's strange environment. He's an adroit mimic and quick study, mentally far superior to the Earthlings. Nevertheless, he sometimes misinterprets the unfamiliar behavior surrounding him. For example, after Elliott decides to take his teen-age brother Mike (Robert MacNaughton) and their kid sister Gertie (Drew Barrymore, a 6-year-old granddaughter of the late great John, who reveals a delightfully impish presence and a stunning sense of timing) into his confidence, the immediate consequence is pandemonium. Gertie shrieks at the sight of E.T., who misconstrues her reaction as a conventional form of greeting and shrieks right back. Perhaps the wittiest single sight gag in the movie is the image of Gertie fleeing in panic with E.T. waddling along in her wake, still imitating her hysterical reaction out of sheer friendliness.

E.T.'s assimilation also suggests a subtler humorous purpose. E.T. seems to embody the process of childhood development and socialization at an accelerated rate. He's constantly outdistancing the siblings as they attempt to familiarize him with the local folkways. He keeps adding new dimensions, evolving from stray pet to playmate, copycat, alter ego, miracle worker, foster parent, mentor and ultimately divinity.

The new dimensions are physical as well. Brilliantly constructed by Carlo Rambaldi, the creature reveals a complex, poetically expressive anatomy. For example, the first and last feature that we're made aware of is his heart, an organ that burns with visible, red-hot intensity in moments of emotional urgency, since his chest cavity is covered by an alarmingly thin, transparent membrane. Later there are equally distinctive, stirring aspects connected with the way E.T. uses his digits, speaks, changes coloration, breathes and moves his eyes.

The screenwriter, Melissa Mathison, had contributed to the script of "The Black Stallion," a movie Spielberg greatly admired. The idyllic friendship between boy and alien in "E.T." clearly echoes the animistic union of boy and wild animal in "The Black Stallion." Even certain details are similar: The M&Ms that Elliott leaves for E.T. recall the sugar cubes Alec left for the stallion.

However, the crucial common denominator between Spielberg and Mathison may have been a compatible streak of mysticism. According to the director, the screenplay took shape with remarkable promptness and unanimity of vision soon after he described the premise to Mathison and persuaded her to expand it into a first draft. "She worked very fast," he said. "Eight weeks later she turned in the first draft and I fell in love with the material. It was one of the best movie scenarios I'd ever read."

While the thematic aspects tend to recall "The Black Stallion," the plot owes more to pictures like "Whistle Down the Wind" and "Escape from Witch Mountain." E.T. enlists the aid of the children concealing him to reestablish contact with the departed spaceship, so that he can return to his own civilization. Despite the devotion of his little helpers, E.T. is threatened in two respects--his physical condition seems to deteriorate the longer he remains on Earth (the malady suggests a potentially fatal case of homesickness) and the hunters continue to close in on his hiding place.

"E.T." proves equally ingratiating as updated fairy tale and family comedy. One can imagine executives at the Disney studio tormenting themselves with the question, "Why couldn't this one be ours?" Spielberg's affinities with Disney at his most intuitive and exuberant have never been more apparent and there are even endearing moments of homage to Disney productions like "Bambi," "Peter Pan" and "The Absent-Minded Professor."

The setting itself appears to hover on the edge of fantasy. Though Elliott and his family inhabit a persuasively lived-in home, it's also strangely susceptible to magical transformation. Situated along the crest of the hillside subdivision, Elliott's house seems only a stone's throw from the enchanted forest where E.T. is separated from his fellow explorers. It's also bordered in the back by that beautiful but incongruous cornfield and lit by that ethereal, gorgeous moonglow.

Without losing sight of its humorous suburban familiarity, Spielberg envisions the home and the entire neighborhood as enchanted landscapes. "The suburbs are more substantive than people know," Spielberg has observed. "I grew up there, and I'm amazed that so few filmmakers recognize how much imaginative stimulation there is to be had in that environment. And I don't mean your uppity, wealthy suburbs like the locale of 'Ordinary People.' I'm talking about Sears, Roebuck suburbia."

Spielberg derives constant inspiration from the geography of the unfinished subdivision, the look of the house and its topography, and the comfortable clutter of its decor. There's no telling when some appliance, toy or piece of junk might lend itself to extraordinary purposes and occurrences. E.T. is eventually inspired to invent a means for communicating with his brethren by fiddling with Gertie's Speak and Spell toy, watching a TV commercial and pondering a Buck Rogers comic strip. From Spielberg's standpoint all that stuff can be fantastically useful and educational. It can inspire revelations.

E.T. is eventually obliged to leave Elliott, but he departs on a transcendant note of reassurance, promising to remain an unfailing source of inspiration to the child. And that reassurance is enough. When the creature places his glowing index finger on Elliott's forehead and says, "I'll be right . . . here," you believe it.

In the closing stages the movie lifts you up and away on surging currents of pathos and fantasy. The celestial effect seems even more pleasing and desirable than it did at the conclusion of "Close Encounters," when Spielberg and composer John Williams conspired brilliantly on a similar quality of illusion.

Spielberg has always demonstrated extraordinary aptitude for filmmaking, but "E.T." is far and away his most satisfying work to date. He knows how to transform the raw material of his childhood into an appealing popular fable. There are sequences that touch you to the quick in mysteriously casual ways: Elliott explaining the functions of his toys to E.T.; the mother reading "Peter Pan" to Gertie while Elliott and E.T. also listen from a place of seclusion; Mike taking refuge among Gertie's stuffed animals and falling asleep on the night when it appears that E.T.'s life may be flickering out.

Spielberg's parents broke up when the future filmmaker was in his teens and this misfortune haunts his most personal movies in curious ways. Barry, the little boy briefly captured by extraterrestrials in "Close Encounters," doesn't have a father; the Richard Dreyfuss character deserts his family after a breakdown. Spielberg has acknowledged the scene came from real life: "It's one of the strongest imprints from my childhood. I saw my father crying for the first time, and I couldn't help myself. I yelled 'Crybaby! Crybaby!' at him."

In "E.T." Elliott is obviously upset by the recent departure of his father. One gathers that this creates a peculiarly receptive psychological state for visitors from distant worlds. Among other consolations, E.T. arrives just in time to help Elliott weather a painful sense of loss. And what a tradeoff! Elliott may have lost an unseen dad but he gains the assurance of divine inspiration.