The cliche' "Better late than never" can be applied wholeheartedly to Fred Schepisi's beautiful first feature, "The Devil's Playground," opening today at the Inner Circle and Tenley Circle. Released in Australia in 1976, it has taken longer to arrive here than any other important movie generated by the recent breakthrough of Australian pictures, including Schepisi's second feature, "The Chant of Jimmie Blacksmith."

The delay is mystifying. "The Devil's Playground" proves to be not only the most original and impressive achievement of the Australian movement but also the most understanding and emotionally lucid.

An episodic comedy-drama set in 1953, "The Devil's Playground" surveys the intensely self-conscious, shame-ridden impulses and confusions shared by the students and faculty at a Roman Catholic secondary school intended to prepare adolescent boys for the Marist brotherhood. Schepisi's semiautobiographical story is a personal, eccentrically funny impression of a calling that fails.

The recollections of an aspiring juvenile monk who washed out early, "The Devil's Playground" reveals a keen and comic perception of the sexual drives and apprehensions that persist in tormenting both the kids and their preceptors, try as they do to repress the call of the flesh.

Schepisi (pronounced "skep-see"), whose first American movie, a western comedy called "Barbarosa," will soon be released, is an Australian of northern Italian parentage. At the age of 13, he did indeed believe that he had a religious vocation, and his scenario reflects first-person experience with a consistency and immediacy that filmmakers seldom achieve.

Schepisi orchestrates the various personalities and attitudes represented by the boys and their teachers and imposes a coherent, sympathetic vision of the environment they inhabit. Obviously, this sort of wide-ranging comprehension would have been impossible for his alter ego, Tom Allen, played by an alert, slanty-toothed juvenile actor named Simon Burke. At the time Schepisi-Allen must have been preoccupied with self-doubt. In retrospect, he puts the self-doubts of an entire community into affecting perspective.

The title springs from a dogmatic cliche' uttered by Brother Frank (a brilliant performance by long-faced, grave-voiced Arthur Dignam), the most demanding and desperately unhappy teacher at the school. Deploring the moral weakness of the student body, he snaps, "An undisciplined mind is the devil's playground." His colleagues, a more relaxed lot, can hear it coming and they playfully jump in and recite it in unison.

Brother Frank is first heard reprimanding Tom, who has thoughtlessly slipped his trunks off while taking a shower: "You must learn that your body is your worst enemy . . ." Later, in the course of two extraordinary sequences, we discover that Frank is speaking from deep, frustrating experience. On a brief holiday he pays a visit to a public swimming pool, sneaking furtive glances at the spectacle of tantalizing flesh that surrounds him. Weeks later, during a school retreat, he dozes off and conjures up a spectacular underwater erotic dream, in which four naked nymphs entwine themselves around him. Even in his dream Brother Frank looks embarrassed.

There's no hostility in Schepisi's exposure of Brother Frank's inability to prevent his mind from wandering. The physical world and stirrings of desire simply refuse to be ignored.

Just about everything in this tangible world mocks the earnest efforts of students or brothers to attain spiritual peace of mind. When Brother Victor, who ordinarily sublimates his carnal longings in excess smoking and boozing, lets his impulses carry him to the outskirts of sex, he panics and rejoins his younger colleague Brother James with a sigh of relief: "They nearly had me. That was close, Jim."

Indeed, the real world is such an incorrigible mocker that the wisest students and brothers have made their peace by calmly compromising with reality. Tom's best friend, John Diedrich as a good-humored senior boy named Fitz, anticipates Tom's secular backsliding and eventual departure from the school. "I hope I die in a state of grace," Tom confides in an early mood of pious sincerity. "You'll probably die playing with yourself," Fitz replies.

Tom's faculty mentor is the aging Brother Sebastian (Charles McCallum), whose tolerant outlook expresses the opposite end of the spectrum from Brother Frank. "You must stop worrying about being perfect. If the life here troubles you too much, give it up . . . It's unnatural to deny life. Half the rules they make here are unnecessary and unnatural."

Brother Sebastian veers a mite close to adorable saintliness, but he has a prophetic sense of Tom's genuine mission in life, realized in the expressive richness of Fred Schepisi's filmmaking style. The idea is summed up in one delightful sequence, set during the retreat. The boys are at the lake, observing a vow of silence. Tom, absentmindedly fiddling with a handful of pebbles, drops one into the lake by accident. The sound attracts everyone's attention. Now deliberately, Tom drops another pebble, then another, sensing the shift in mood from unnatural sobriety to spontaneous playfulness. Soon the entire group is merrily chucking pebbles into the lake, and joy reigns supreme. "The Devil's Playground" is a comic odyssey that documents the stirring of a responsive, life-affirming vision from the remains of a misdirected religious impulse.