ALTHOUGH I can recall an awful lot of time spent watching the forties films that played on TV through the fifties' rainy afternoons, most of those I saw I've long since forgotten. Even at the time, if I remember rightly, they all seem to have been about the same three girls, tall and sunny with cascading curls that reached down to dust their great, husky shoulders, while they sang their way good-naturedly through the GI bases of the world.

But, even as my picture of each of those films was blurring into its successor, I had begun to understand how each provided a private entry into both my parents' past and, to some extent then, my own.

I was only around for the last year of the forties, but I sometimes liked to flatter myself into pretending that I could almost imagine what that decade must have been like. They say my father looked like Jimmy Stewart then and my mother tried to wear hair like Veronica Lake. And I could almost believe it-even though my father and Jimmy Stewart have long since aged in opposite directions while my mother's face took on the lines and wrinkles by which, as a child, I had learned to identify my grandmother and great-aunt-mostly because the stories they would tell seemed to correspond with those of the movies I had seen.

I could almost imagine the appropriate fade-ins and outs when my mother spoke so enthusiastically of serving Sunday brunch at the local USO, of the constant stream of boys that could be met on the endless series of trains she traveled between Boston, New York and Maine, of the year she spent in Washington-she tells of that too-haltingly translating Rumanian for some hastily assembled war office into a coded English she understood even less.

My father, as befits the characterization, is much more reticent. But there are nonetheless the occasional reminiscences of flying into London on a choked night, and of holidays in the English countryside which finally came to an end when one of his buddies decided to marry the daughter of the owner of one of the homes in which they used to stay.

BUT, then, last year, I saw Paula Prentiss, the tough, erotic nurse in Catch-22, stretch out naked in the languorous sunshine, and, in the process, blot out all the images of the forties I had worked so hard to accrue. The same thing had happened the year before when Jane Fonda's Gloria ( They Shoot Horses, Don't They? ) had come to dominate my sense of the thirties, and two years before that when Faye Dunaway's Bonnie ( Bonnie and Clyde ) tried her hand at the same. Now I have no trouble with all the old movies I've seen on TV. For as much as they directed the manner of the lives my parents lived, they also reflected those lives to me. And now when I look at those films the moments in which they appear not so much slick as clumsy, silly and self-indulgent are just when they seem most real. But when today's films try to recreate those times, they leave out all that would make them appealing. In fact, they are too well made, too self-assured. Their images loom before your eyes and deny the workings of your own imagination. They create a past with which there can be no quarrel. Paula Prentiss supersedes all the memories that she should evoke.

And so we forget that true nostalgia demands commitment. Freshman year when I was supposed to be working at shelving books on the second floor of Lamont, I spent much of my time surreptitiously paging through the old bound volumes of Life and the Saturday Evening Post; for my effort, I really think I came much closer to the past than I did by reading Life's recent "Nostalgia Issue" in a dentist's office last month. For memory isn't something that can be served up at the enterprising whim of some features editor or film producer; it's an ephemeral commodity. A dozen times a day, if you should be so lucky, memory will brush your ear or dance before your eye. But you can never quite catch up with it or hope to track it down. You are aware of living a life that has a certain depth in the evasive dimension of time, but you're crazy if you try to be precisely sure of ever having been there before. The past just can't be made that definite-its fascination is, in essence, its elusiveness.

ROBERT MULLIGAN'S Summer of '42, by virtue of its being so self-certain in its aims and so generally competent in its methods, challenges this very idea of memory's fragility. The film's simple story-that of Hermie (Gary Grimes), a quiet, fifteen-year-old boy on the verge of both first love and first sex-is almost beside the point. It is quietly and sensitively told, and well-acted by a trio of neophyte actors, but, I would suspect that even for fifteen-year-old boys, the story is nonetheless something of a bore.

What makes the film so attractive is its attempts-by director Mulligan, cinematographer Robert Surtees, and art director Al Brenner-to reestablish a visual landscape that reflects the lonely beauty of coming-of-age on the borrowed time of a world that is everywhere else embroiled in war. The film's landscapes-fields of brown and orange, hazy skys often muted by low-hanging clouds-are like Wyeth paintings that have taken on life with a well-nigh imperceptible sigh. Its interiors are like Norman Rockwell covers that have burst forth into an engaging kind of action.

In many ways it's an idealized environment, of course, but the fact that the film is framed by the spoken reminiscences of Hermie's adult voice, could possibly justify its mood. The film asks to be taken as a memory, the type of memory that has been tidied up and simplified by the ameliatory processes of time. Except that Summer of '42 goes too far along this line. It presents its memory as a cohesive, dramatic whole. It's too neat to be a memory.

The young girl (Jennifer O'Neill), a war bride living in a lonely cottage on a promontory where sea, earth and air come together, who becomes the focus of Hermic's discoveries, is presented with the necessary elusiveness of a dream (partly as a result of Mulligan's treatment of Herman Raucher's often underwritten and coy screenplay). But, because of the realistic, often comic development of the rest of the film, her character calls forth audience frustration rather than the desired sense of intrigue. Introduced in two slow motion sequences, she is surrounded by a lyricism that is forced and contrived. Throughout the middle of the film, as she invites Hermie into her house and proceeds to knight him her friend, the audience is thrown back on its own expectations-is she as simple as she seems? Is she not perhaps a younger version of the spinster/widow-in-heat that dominated the films of the fifties? The movie's conclusion-a beautifully paced, remarkably tender love sequence-resolves some of the confusions, and the film reverts back into the remembered memory on which it began.

Summer of '42, however, is often best when it abandons the pretense of remembrance altogether, and becomes instead a conscious, and occasionally unwitting, comment on the artificiality of movie-reality and its influence over its audience. And so we see Hermie and his sidekicks going to the movies-Bette Davis in Now, Voyager is on the screen-and trying to feel up two teenage imitations of Jean Harlow. In the next scene, as Hermie prepares to visit his war bride, he is rehearsing lines like "Laughter becomes you" to get him through his embarrassment. His efforts to ape affectedly "adult" cultural pretenses are in direct contrast to those of modern movie audiences, where more often it seems the adults mimic the young.

The film is also infused with a Michel Legrand score that is at once appalling and appropriate. Its romantic attempts to tumble into poignancy echo Francis Lai's Love Story theme, but here the music seems to actually reflect the true excesses of its period. In fact, in the film's climactic scene, Hermie places a big band treatment of the film's theme song onto the phonograph, and, in the wonderful moment that follows, the two realities-that of purported, remembered history and blatant movie artificiality-merge. Like a mobius strip, the film turns back on itself and, for just that second, captures some of the clumsiness and fun that can be had from authentic old movies.

But Summer of '42 is still a contrived memory, unblemished by the time that supposedly separates the film's characters from ourselves. It demands a set response, rather than triggering individual reactions. It is too large, too pat. For the past is nothing if not fragmentary and one's own. And to fall for someone else's slicked down version, is to deny yourself the real satisfactions of remembrance.