“My goodness, what beautiful diamonds!”

“Goodness had nothing to do with it, dearie.” This famous exchange, between an envious hat-check attendant and a Gotham good-time girl played, with typical hieroglyphic panache, by Mae West, is from “Night After Night,” a 1932 production from Paramount Pictures. The wisecrack, the actress, and the plot – a socially ambitious speakeasy owner discovers that the upwardly mobile suffer from heavier constraints than just gravity – typifies a time in American culture when the gloves came off and sexuality competed with love as the movies’ hottest subject.

Film Forum’s month-long survey, “Paramount Before the Code,” which starts today, features 46 films from one of Hollywood’s top studios, which will reintroduce viewers to a startling period in movie history. A faster, racier, more sexually open culture followed World War I, but it wasn’t until the introduction of sound film in 1927 and the collapse of the stock market in 1929 two years later that the frenetic lives more and more Americans had been living hit movie screens in full force – for a short time.

Economic turbulence and a new competitor, radio, challenged Hollywood, just as television would in the 1950s and the Internet does today. Then as now, studios responded by giving their audiences the extravagant, the fantastic, and the scandalous, so that they might revel in it or condemn it (or, more likely, do a bit of both). Already prized for its sophisticated style, Paramount went further than most other film companies and allowed a franker sexuality in its pictures.

The studio unleashed its formidable directing crew – Cecil B. DeMille, Ernst Lubitsch, Josef von Sternberg, and Leo McCarey, among others – to add titillation to historical spectaculars, romantic comedies, and urban melodramas. They found Marlene Dietrich, with her audacious wit and style, in Berlin and brought her to America to take on MGM’s Greta Garbo; hired stars notorious for uninhibited romping like Tallulah Bankhead and Mae West; and larded DeMille’s “respectable” productions with ever-more flesh and innuendo.

“You know what they say,” Groucho Marx cracked in “Monkey Business,” another Paramount film. “When love goes out the door, money comes innuendo.”

The festival features priceless comedy, such as Lubitsch’s 1932 masterpiece of love, intrigue, and grifting, “Trouble in Paradise” (June 24 & 25), as well as Edward Sutherland’s 1933 “International House” (July 7). With a lineup of stars cast from so wide a net (W.C.Fields, RudyVallee, George Burns, and Gracie Allen) you wonder how everybody on the set of this one shut up and made the movie.

In DeMille’s once hugely popular (now overwrought, even appalling) Paramount epics, pomposity, piety, and salaciousness produce spectacles of delightful if inadvertent camp. Who can forget Claudette Colbert, in “The Sign of the Cross,” taking her midday bath of asses’ milk? Paramount techies calibrated the milk in the marble pool to rise beneath, but not quite cover, Colbert’s breasts, as she listens to gossip from a (female) Roman confidant and responds: “You’d better take off your clothes and come in here with me.” Or what about the lesbian snake dance intended to seduce a hapless Christian? Or those buxom, unclothed Hollywood glamour girls (playing Christian maidens!) devoured in the Coliseum by lions, gorillas, and a lewdlooking alligator?

“Girls About Town” (June 26), an almost-forgotten 1931 comedy, makes a comeback in the festival. In this early effort by director George Cukor, his trademark elegance of style is already evident: The picture opens with a gorgeous montage of young women making up their faces in the ladies’ room of a swanky nightclub. Its heroines are adept at cultivating the interests of affluent out-of-towners. Kay Francis’s character is tired of being “pawed by a bunch of middle-aged Babbits” and wants a real romance; her friend (Lilyan Tashman) clings to fewer illusions – “I’ve got a callus on my knee from my ‘boyfriend’s’ romantic approach!” She isn’t about to relinquish their Midtown Deco apartment to settle down.

This movie is a textbook example of how Paramount teased audiences while evading a gathering mob of indignant censors. There is plenty of saucy language but no profanity; it’s obvious that money for sex is involved in the girls’ lucrative doings, but prostitution is never mentioned. And while the movie may be drenched in what some considered a decadent lifestyle (other viewers might find themselves wishing New York life still crackled with such wit and sophistication), traditional goals – love and marriage – remain paramount.

Like all good things, this giddy frankness didn’t last. By 1933 the legion of Decency united Catholics, fundamentalist Christians, and Jews unsettled by changes in the culture (and eager to blame Hollywood for them). The Legion flamed with warnings over where a hedonistic America would lead us, insisting upon a “cleaner,” “decent” Hollywood. By the end of 1934, Hollywood put into action its Production Code and began toning down its movies: as the code stated, “no picture shall be produced which will lower the moral standards of those who see it.”

This may have satisfied the protestors, but it was a disaster that American film is still trying to get out from under. The breath of candor and freedom that motivated moviemakers and audiences in the early 1930s was smothered before it could lead to work that would invigorate the film culture, rather than just bring scandal to it.The ridiculous strictures of the Production Code forced stars well into their 30s to play wide-eyed virgins and forbade onscreen married couples to share a single bed.

The code eliminated any “perverse” political or social subtleties, and thereby diminished, even infantilized, American film.Although a few films (mostly from abroad) were seen in spite of it, and a few later films brilliantly subverted it (“Casablanca”and “Miracle of Morgan’s Creek” are two examples from the 1940s), lying about sex, love, and life was not only institutionalized, but it became essential to commercial success. And though the code was disregarded by the late 1960s, it’s still a profound influence. Many of Steven Spielberg’s films, with just a little snipping and bleeping, could be passed under it.

“Paramount Before the Code” suggests the better world that could have existed. Perhaps most interestingly, it shows how offbeat and original Hollywood could be when it wasn’t spending time looking over its shoulder. In 1933’s “Duck Soup” (June 24 & 25), Groucho, rallying his troops before combat, points to Margaret Dumont and shouts, “And remember, you’re fighting for this woman’s honor – which is probably more than she ever did!” But if the Marx brothers were the irreverent kings of precode Paramount, Marlene Dietrich was its undisputed queen.

Dietrich offered a view of sexuality more candid, threatening, and intensely ravishing than any other star of her time, or ours. Paramount billed their hot property as the female star “even women love,” a hint at Dietrich’s multilevel allure. “Blonde Venus” (June 24 & 25) has an opening sequence so explicit it was removed from most prints: Dietrich and a few chorus-girl friends skinny dip in the Rhine, spied upon from the woods by American hikers. This scene was said to have added credibility to the Legion of Decency’s complaints, but the “Hot Voodoo” number later in the picture must have stunned nearly everyone.

Before Dietrich’s entrance, a chorus line of faux Africans shimmy onstage, while a gorilla shambles into the nightclub – then, suddenly, the gorilla removes a furry paw, and we see beneath it the hand of a pale, lovely woman. Never mind the gorilla’s head popping up to reveal Dietrich underneath, never mind “Hot Voodoo’s” provocative yet laughable lyrics. That moment of transgression, the beast’s hand becoming a beauty’s, that convergence of feared, animal sexuality with the ultimate treasure, retains remarkable power.

The issues of authority and freedom always at stake in our lives (especially our sexual lives) are the predominant themes of the films Dietrich collaborated on with von Sternberg. Most of these – ravishingly shot and designed – are included in the Film Forum series. Don’t miss 1930’s “Morocco” (July 20), Dietrich’s second film with von Sternberg but the first released in the U.S. (the earlier, German-made “The Blue Angel” worried even Paramount).

Playing another nightclub entertainer, Dietrich sings to her audience wearing a man’s top hat and tails. She asks a pretty girl seated at a table if she can take the gardenia in her hair; flower in hand, Dietrich then kisses her on the mouth. Even the extras seem surprised, laughing and cheering as Dietrich sniffs the flower and saunters off, an androgynous lothario fresh from a conquest. There’s never been a sexual moment on film as unexpected and exciting as that one in “Morocco.” It transcends the exploitative silliness of sexual shenanigans in other films of the day, and reminds us of what, today, remains possible in so public yet intimate an art.

Until July 21 (209 W. Houston Street, between Sixth Avenue & Varick Street, 212-727-8110).