Since 1927, when the Academy of Motion Pictures Arts and Sciences was founded “to raise the cultural, educational and scientific standards” of American filmmaking, the Academy Awards traditionally have been the time when the film biz puts its best face forward before a billion or so adoring fans around the globe.

Despite some embarrassing moments, borne of the Oscars being a live broadcast presented by world-class spotlight lovers, the Academy Awards normally have featured exalted and honorable successes by some of our best-loved movies.

The presentation of the award for best picture – the only category whose nominees and winners are voted upon by the entire Academy membership – provides the defining moment when Hollywood holds its collective breath.

A brief tour through the 66-year history of the best picture category offers a fascinating glimpse not only at U.S. film history of the sound era, but a unique reflection of American cultural history writ large on the silver screen.

The selection of the best picture Oscar, much more an art than a science, is subject to the vicissitudes and trends of Hollywood film culture as well as to its own unwritten laws. For example, it has become common knowledge that spectacles and epics are favored over intimate dramas, that movies espousing “good causes” are treasured, and that comedies are barely noticed at all.

Musicals such as “My Fair Lady” and “The Sound of Music” – consecutive winners in 1964 and 1965 – seem to be a dying breed. Westerns rarely have won best picture, but Clint Eastwood’s “Unforgiven” has reinvigorated the genre and led to a new wave of quality Westerns, according to industry observers.

Much is rightly made of the existence of a greater or lesser number of fine movies in a given year, leading to excruciating choices, or embarrassingly weak fields. Without disrespecting 1994’s movies, many movie execs have lamented the lack of best picture-caliber films this year.

Conversely in 1939, voters chose “Gone With the Wind” out of a field that included all-time greats “Stagecoach” and “The Wizard of Oz.” Two years later, “How Green Was My Valley” won against a field that included classics such as “Citizen Kane” and “The Maltese Falcon.” (“Kane” won only a single Oscar, awarded to Herman Mankiewicz for best original screenplay.)

During the ’30s a single studio dominated the best picture category. In MGM’s golden age, the house that Mayer and Thalberg built won Hollywood’s ultimate accolade more often than not, with productions like “Mutiny on the Bounty” and “Gone With the Wind.”

During World War II, stirring war pictures like “Mrs. Miniver,” “Casablanca” and “The Best Years of Our Lives” took home the statuettes. Riding that trend, “The Best Years of Our Lives” picked up the picture pick for 1946.

In the ’60s England demonstrated its clout with a string of epic, period costumers: “Lawrence of Arabia,” “Tom Jones,” “My Fair Lady,” “A Man For All Seasons” and “Oliver!” These films – produced, directed or acted by Brits – won for best picture in five of seven years.

It wasn’t until the ’70s that Hollywood’s growing proclivity for violent pix and tougher, edgier subjects began to surface in the Oscar selections. In rapid succession, pix like “The French Connection,” “The Godfather,” “The Godfather Part II,” “One Flew Over the Cuckoo’s Nest,” “Rocky” and “The Deer Hunter” took best picture.

Then, sensitive American dramas heralded the coming of the ’80s: “Kramer vs. Kramer,” “Ordinary People” and “Terms of Endearment,” a wonderfully directed “dramedy” with great acting by Jack Nicholson and Shirley MacLaine. The early ’80s also included two more British-directed period pieces: “Chariots of Fire” and “Gandhi.”

The past 10 years have featured an eclectic blend of movies, emblematic of Oscar’s affection for spectacle, politics and memorable performances. “Terms of Endearment” was a wonderfully directed “dramedy” with great acting by Jack Nicholson and Shirley MacLaine.

The exotic, lushly photographed “Amadeus” (1984), “Out of Africa” (’85) and “The Last Emperor” (’87) were perhaps greater looking than they were great films.

Oliver Stone’s “Platoon” (’86) may have speeded the country’s coming to terms with the Vietnam War. “Rain Man” (’88) and “Driving Miss Daisy” (’89) were touching, well-made films. “Dances With Wolves” (’90) had everything: spectacular photography, an epic theme and humanistic politics.

“The Silence of the Lambs” (’91), one of the darkest films ever nominated, also was the first flat-out thriller to win top honors. In 1992, “Unforgiven” revived the Western and rewarded producer/director Clint Eastwood with the enduring respect of the Hollywood community.

And in 1993 – which was thought by many film critics to have been one of the strongest film years in decades – “Schindler’s List,” a black-and-white film about the Holocaust directed by the top-grossing filmmaker in history, was triumphant.

Steven Spielberg’s graceful, eloquent movie has had an enormous impact around the world for its unflinching memory of one of the 20th century’s most painful and shameful times.

At Oscar time, Hollywood’s eagerness to serve as a cultural conscience overcomes, at least for a time, its tendency toward commercialism and boilerplate filmmaking.

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