OF all King Arthur's knights who sought it, only Bors, Perceval, and Galahad ever reached the Holy Grail. These only were worthy of the quest, for they were pure of heart. The Grail, the legendary cup supposedly used by Jesus during the last supper, has symbolized wholeness, healing, union with the divine, and fulfillment since the Middle Ages.There are many versions of the Grail saga, and the very latest, Terry Gilliam's dazzling "The Fisher King," relocates the legend to the late 20th century on the streets of New York. The city may be an odd place to find the virtues this film celebrates, but Mr. Gilliam's bold style with Richard LaGravenese's fine script make Arthurian chivalry seem viable downtown. The dragons, giants, monsters, and evil knights of yore translate quite easily into contemporary terms. Because "Fisher King" is a Grail quest film, we know from the beginning how it will end. Viewer satisfaction comes in anticipating the reenactment of the romance and in watching Gilliam's and LaGravenese's reinterpretation. They stay true to the medieval dream-like narrative and the chivalric code, but it's the 20th century's penchant for complex characters that makes it all feel plausible. The homeless, the mentally ill, and the lonely live side-by-side with the unsatisfied materialist on the streets of this film, and Gilliam spares no camera angle in portraying the chaos and sorrow he sees there. But as realistic as it is about contemporary horrors, "Fisher King" proposes no political solutions to the social ills it so graphically depicts. Though it compassionately portrays the urban jungle's homeless citizens with peculiar clarity, the film is not about homelessness per se, anymore than it is about mental illness or AIDS. It is really about the hunger for redemption from these things, the need to search for truth and to respond with love to those around us. In its humanistic way, it is about the liberating quality of unselfish affection, and about how man must learn to ask the right questions, to take responsibility for his actions. It suggests that love is the means to healing the dilemmas of the times. It is a daring work of art, and as such, open-ended enough to prevent it from feeling like a sermon. When a rich, cynical disc jockey named Jack Lucas (Jeff Bridges) barks his hate-filled, mean-spirited message into his mike late one night, a troubled listener takes this message to heart. Jack's ill-chosen words trigger a massacre. He will spend the rest of the film trying to redeem himself by helping one of the victims of the tragedy, a mad Perceval-Don Quixote named Parry (Robin Williams). Formerly a professor of medieval literature, Parry contracts his assumed name from "Parzifal." But Parry will soon be seen as the Fisher King, the wounded monarch who can only be healed by the Grail. It is Jack who must take on the persona of the "fool" Perceval who seeks the Grail because he wants to help the king. "Fisher King" is the most blatantly religious American film since "Places in the Heart," and only a filmmaker of Gilliam's outrageous boldness would have had the fortitude to risk it. "Fisher King" raises questions (about the quest for truth) and suggests answers (in the nature of love) that are basically theological in nature. In the end, it is only the redemptive power of love (human affection, in this case, purified by unselfish motives and touched by divine grace) that redeems both men from their ter rible suffering. In a recent interview LaGravenese was asked how he dared take on the subject of redemption in an American movie. "For me it is the only subject right now," he says. "What I meant to say with this film is that the only way for [man to evolve further] was to find the "fool" within - that is, the innocence, the wonder, the awe we have lost along the way. The one who is innocent (the pure in heart) sees only the service that needs to be rendered. "In creating Parry's character I wanted to create a fool - an innocent childlike character - who would open the door and lead Jack on his journey, because the story is really about Jack's [growth]." LaGravenese points out that it isn't the attaining of the Grail that helps Parry so much as it's Jack's gradual process of change. "What's important are the moments that make up your life.... Jack realizes no matter how much he has, he has nothing...." What can fill that empty space but love? he says. The laws of chivalry still have metaphorical resonance for us today because, says LaGravenese, "There is a part of godliness that is a warrior and must be a warrior and stand for the truth."