FOUR men spend a weekend eating themselves to death in a grim, overdecorated mansion: the conceit has the imprint of an allegory by Bunuel, the echo of wild house parties in Italian movies of a decade ago, the teasing metaphysics of a "Last Year at Marienbad." Four men tied to a brotherhood pact that tests endurance --the premise is also a kinky Continental variation on "Deliverance."

Marco Ferreri's "The Grande Bouffe" trips over prize-winning foreign films of the sixties, tickles us with memories of Fellini and Resnais and Bunuel, of Antonioni and claustrophobic chamber works by Bergman. But the movie's greatest debt is not to the preceding era's prestigious portraits of European decadence but to the laws of the universe--the ways of the world--as the porno movie sees them. Ferreri's is a porn epic in the grand manner, a mordant, chilling, hilarious dirty movie that, for sheer audacious lubricity, out-tangoes "Last Tango in Paris" and almost gives the devilish Miss Jones a run for her money.

Like "Last Tango," "The Grande Bouffe" derives added shock value from the presence of stars: it's not Linda Lovelace, but respectable people like Marcello Mastroianni and Ugo Tognazzi taking the chance of their careers, letting loose, talking dirty, abandoning themselves to the urges of the unleashed libido.

Ferreri has set out with a fierce will to challenge audience sensibility, and his Rabelaisian romp establishes new levels of rauchy foul taste in art house--as distinct from 42nd Street--porn movie fare. In manner and matter, Ferreri is working on a level that the makers of "Deep Throat" could not --and would not--aspire to, but his movie's lifelines are decidedly pornographic.

The first law of the true-blue porn movie is the tyranny of the flesh: we dont see the characters in "The Grande Bouffe" otherwise occupied than at the feast, their one obsessive, consuming goal the constant satisfaction of the senses. Locking themselves away from the world in a mausoleum of a house and shedding civilized restraints, Ferreri's cardboard figures are participants in a porn-movie banquet, questers in search of absolute freedom. At their non-stop weekend orgy, food and sex are available in unlimited supply, and as with the Linda Lovelaces and Felicity Splits of the blue-movie screen, too much is not enough for these celebrants. Once embarked on an orgy of tasting and touching, they are powerless, imprisoned rather than liberated by the spirit of Dionysus.

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There's no joy at Ferreri's table: their passions and appetites spent the revelers have no place to go. It's the presence of melancholy and death in the face of a sensational bacchanal that distinguishes Ferreri's feast of carrion from its lowbrow cousins. Characters in porn movies are evaluated with regard to their sexual prowess and their freedom from guilt, and they are never more than temporarily unhappy: more frequent and more intense sex can solve any passing malaise. But here, the pleasures of the flesh are but harbingers of the coffin, and Ferreri's pestilential houseparty is, finally, a warning, an exemplum, an inverse appreciation of bourgeois restraint.

Porn people, those guiltless joy-seekers, may inspirt our envy and ignite our lascivious fantasies, wheras Ferreri's party-makers have only our pity, and our disgust. In porn, and in "advanced" movies of the sixties such as "La Dolce Vita," say, or "L'Avventura," decadence and dissipation are chic, inviting; the houseparty in "The Grande Bouffe" is entirely without glamour. You'll remember in "La Dolce Vita" the character of Paola the Innocent who represents the possibility of a higher and finer life than the one Marcello slips into. Here, Marcello has no options--he's sunk, irretrievably, in a swamp of self-indulgence.

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The movie entertains no visions of romance or purity. The eaters have nothing beautiful to look back on, having left behind--in the world outside their death-trap--crummy, undistinguished lives. Stripped now of the final vestiges of self-respect, they devote themselves to total self-abasement. (And the women who are their companions in degradation are in every way their moral equals.)

Adapting the audacious lawlessness of the porn movie to his Swiftian demolition of untrammeled appetite, his parable, as many critics have read it, of the collapse of modern society, Ferreri has arrived at a tantalizing blend: the dirty movie with the heart of an impassioned medieval moralist. The director has the puritan's inevitable fascination with sin and corruption: he's titillated by what he shows us, but he's repelled, too--and it's that moralistic disapproval, that unconcealable sense of shock, that separates his work, for all its salacious preoccupations, from that of the true, unstricken pornographers.

Morality aside, "The Grande Bouffe" is a liberatingly funny pitch-black comedy. Ferreri assaults us. You're bound to be caught off guard by the overheated outhouse humor, the bloated, fetid atmosphere, the absorption with vomit and excrement, the colossal disrespect for human anatomy. Like pornography, it turns us (whether we're willing or not, and if we pay our pornmovie price of $5 we certainly ought to be willing) into voyeurs and accomplices. It appeals to our prurient curiosity at the same time that it disdains erotic indulgence. The movie tests our limits of shockability: how much can you take, Ferreri seems, combatively, to be asking.

His theme is the folly of moral anarchy, but Ferreri himself holds back: he is a strict, even severe director who allows not one arty shot or lyrical moment to intrude onto his bleak canvas. Slowly, carefully, his film builds, snaring us by its opposing tensions. Porn brushed with intense moral vigilance, the movie keeps turning on itself, proffering and withdrawing erotic titillation, discovering laughter and terror in the retreat from social restraints.

One of the most tantalizing dissonances is the work of the superb actors, who keep insinuating real pathos and depth beneath the gaudy surfaces of their dirty-cartoon-strip characters: one lost, soulful look from Marcello, one hurt glance from Andrea Ferreol (the actress who plays, unforgettably, the concupiscent schoolteacher who outlasts them all), and the eaters who are bent on turning themselves into trash become momentarily sympathetic--real people that we feel can still be "saved." Convulsed by laughter that chokes, we're depleted by movie's end, having been through a cathartic, unlovely experience: the orgy as death-kit.