LAST TANGO in Paris won't be shown in Boston until April, and perhaps that's just as well for the sake of earlier films by Bernardo Bertolucci which will be around before then. The Conformist, which had its fair share of attention when it came out in 1971, will soon be showing at two local theaters. And now Before the Revolution, the film which won Bertolucci international renown at 23, returns to the Square together with The Spider's Strategem, a film made in 1969 for Italian television but released in the United States only this year.

Less political, more lyrical than his later work, less self-conscious, and more romantic, The Spider's Strategem is a film of a kind Bertolucci is unlikely to make again. Structured around Jorge Luis Borges's little story "The Theme of the Traitor and the Hero," it is a film of limited ambitions shot with remarkable sensitivity and control. Its limit is a lack which might not be noticed except in comparison with the political and psychological ponderings of Bertolucci's other films, a moral core which is absent because of the source chosen. Borges's stories are self-admitted "plots for stories that could be written," devoid of flesh and particulars. They work at the level of things that could happen--paradoxes and self-questionings. If they cease to be general, they lose their point.

Bertolucci and his collaborators on the screenplay preserve the paradoxes, but only at the necessary cost of neglecting motives and character, and building a buffer of mystery between individuals. In a little Italian village, the son of a local hero of the opposition to Mussolini returns seeking the murderer of his father. Like Lincoln, the hero was shot in a local theater--during a performance of Rigoletto. Like Macbeth, he had been warned by gypsies of his impending death. Like Caesar, he was found to have on his dead body an unopened letter with the same prophecy--previously handed to him by a mysterious man on a motorcycle. His is the epitome of the deaths of all great political martyrs--high drama that turns all the world into a stage--but the villain remains anonymous.

THE MOOD is one of distance, quiet, and mystery. Characters walk alone through courtyards edged by arcades shadowing old men, scenes recalling the surrealist architectures of De Chirico's paintings, or through landscapes of over-powering perspective: maize fields that extend to the horizon, forests so carefully cultivated that their trunks establish a sort of grid sweeping off behind the actors. Against such backdrops, human figures appear tiny, lost, joined together only be sweeping pans or long, fluid tracking shots. Narrower perspectives guide the eye: corridors that open out of a stuccoed wall, an avenue of tall poplars leading to the house of a rich local land owner.

Bertolucci turns an equally sensitive eye to shade and tone. Stucco covered by luxuriant ivy, the red tile roofs of the village when the sun is high, are played off against a haunting night-time blue in which lamps stand out in the windows, or, in one stunning scene, a fire leaps up and down, leaving a lingering after-image on film pushed close to the limits of its sensitivity.

For sheer deftness, in a film that flaunts its director's skill, perhaps the finest scene is one in which the son and one of his father's friends inspect a room full of round Italian salamis. Bobbing in front of a pink wall, the salamis swing in and out of focus, all at different depths, reflecting the shapes of the actors' heads as they sniff the curing meats and talk.

THE LONG, complicated camera movements which seem to be Bertolucci's forte give the film a sense of strangeness: not understanding exactly how the camera could get from there to here is like the mystery of the action itself. The original story was already a kind of murder mystery, and to that Bertolucci has added a sense of the menace and consternation felt by the hero. On his first night in town, he is inexplicably locked into a stable; when he opens the door one morning he is punched in the face by an intruder we never see.

But I won't tell you the full nature of the paradoxes, or how they are solved, and I wouldn't advise reading the story first: brilliant as the cinematography is, the film needs all the mystery it can muster to maintain interest. It's a film wrapped up in itself, just as the young man finds in the last scene that the village is cut off from the rest of the world, the tracks leading out overgrown with grass. It enters into no real moral grapplings; even its politics are just subordinate to tricks in the plot. More didactic concerns are left to Bertolucci's other films. What The Spider's Strategem demonstrates above all is his stunning technical finesse.