According to director Bernardo Bertolucci, "Luna" originated in images that welled up mysteriously from his unconscious: the face of the full moon glowing against a dark sky; a mother bicycling with her rapt infant along a road illuminated by moonglow.

These images are reproduced early in the film, and they impose a mysterious evocative power. Bertolucci's problems -- and ours -- begin when these haunting, infinitely suggestive images are transformed into thematic building blocks for a scenario fabricated to explore the deep emotional affinities between a mother and her son.

Bertolucci may express a form of artistic presumption that's peculiarly Italian, shared to some degree by Italian-American directors like Francis Coppola, Martin Scorsese and Brian DePalma. Very sophisticated pictorially, they are inclined to believe that a succession of portentous images or ex plosive climaxes will lead to shattering revelations. When inspiration fails, as it certainly does in "Luna," you're left with the maddening spectacle of portents devoid of meanings.

Jill Clayburgh has the thankless task of embodying Bertolucci's baffling symbol of motherhood, an American opera star who agrees to take her 5-year-old son, played by newcomer Matthew Barry, on a summer tour to Italy following the sudden death of her husband. The evidence suggests that the heroine, absorbed in her own art and career, may have neglected the care and nurture of her child.

The initial scene-setting is inconclusive, but something is tangibly wrong when Bertolucci pulls the first of serveral Shocking Revelations: In addition to suffering from a mere identity crisis, the boy is also a drug addict. This discovery is made by mother and audience simultaneously. It seems a little contrived, since Barry a spunky presence, never suggests the slightest hint of clinical distress. Moreover, the discovery scene is shot in a way that obscures precisely what has been discovered (mainly through a poor choice of camera angles), leaving the verification for subsequent episodes.

Then the scenario really goes whacko. Mom never seeks medical advice, an oversight that seems unforgivable if the addiction is meant to be taken seriously. Maybe it isn't. When the boy gets such a craving for a fix that he jabs a fork in his arm, Mom show her peculiar notion of solicitude by sucking the wound, then sucking the kid while simultaneously massaging his trousers.

Steamy as it appears, this torrid interlude has no dramatic significance. It's in the nature of an incestuous tease. Later, facing his same old problem of a story continuity that somehow seems to be going nowhere, Bertolucci inserts another sensation. Mom drags son into a bedchamber and begins murmuring such tender endearments as, "Now prove you're a man . . . I didn't want to be touching him (i.e., a recently ditched suitor), I wanted to be touching you . . . My baby, my baby, your back is so soft" . . .

Clayburgh's solicitude for Barry may have been the only thing that saved this whatsis of a sex scene from degenerating any further than it does. At a press conference following the film's showing at the New York Film Festival, Bertolucci said that he was prepared to let his Magic Moment go as far as the actors were able to take it. In a separate press conference, Clayburgh confessed that she never had any intention of subjecting the kid to consummate provocation.

Again, having staged a lavishly portentous climax, Bertolucci seems to attach no particular significance to it. On common-sense grounds, Clayburgh's character would have condemned herself as one of the sorriest excuses for a mother even presented on the screen. But apparently no hyped-up confrontation is too shameful for Bertolucci or his loony characters. Evidently, all that's happened is that mother and son have kind of cleared the air, gotten the old conflicts out in the open. The movie concludes on a mystifying yet positively insipid note of affirmation.

What's it all about? Since your guess is as good as mine, make what you can of Bertolucci's interpretation: "I think this movie is made up of an idea of dramaturgy that is different from classic dramaturgy. The goal is to give a kind of pleasure to the audience . . . The characters sometimes dance a kind of ballet of incoherence and contradiction, because they are acted on by their unconscious, and the audience must respond. To me the structure . . .

"The movie should say to the audience, 'I desire you,' and after that the audience must respond. To me the movie say, 'I love you.'"

Keep your hands to yourself, Bernardo.