In his audio commentary for the 2003 special edition DVD of Casablanca, Roger Ebert says the film probably appears on more "best of all time" lists than any other movie -- including Citizen Kane. Why? Because Kane tends to appeal more to film scholars than to regular people, while Casablanca is universally beloved. Even people who "don't like" old movies or black-and-white movies like Casablanca. By 1977, it was the most frequently broadcast film on American television, exposing it to millions of people who otherwise scarcely watched movies from the 1940s. But why is it so popular? Why, of all the movies in all the world, do so many people choose this one as their favorite? Grab your letters of transit and let's investigate. The praise: Casablanca won the Oscars for best picture, director, and screenplay, and was nominated for lead actor (Humphrey Bogart), supporting actor (Claude Rains), cinematography, editing, and music. The American Film Institute ranked it No. 2 on its 1998 list of the best American movies of all time, and No. 3 on the 2007 revised list. (It swapped places with The Godfather; Citizen Kane was No. 1.) It's the 14th-highest rated film by Internet Movie Database users. In 2006, the Writers Guild of America, West voted it the best screenplay of all time. The context: Plenty of books and articles have documented the making of Casablanca, and one thing they all agree on is that nobody involved thought they were making anything particularly special. In fact, there was a pretty solid chance the movie was going to turn into a disaster. It was adapted from an unproduced play that Warner Bros. had bought for far more money than the usual unproduced play fetched in Hollywood. Production was delayed six weeks from its original start date, and by the time it was finished, the movie had gone over budget. The film had to be shot in sequence (highly unusual, then and now), for the simple reason that the screenplay wasn't finished yet when they started. Leading lady Ingrid Bergman was a full two inches taller than Humphrey Bogart. Countless movies have turned out rotten for reasons far less complicated than these, but somehow Casablanca came together. Warner Bros. bought the rights to the play, called Everybody Comes to Rick's, a few weeks after the bombing of Pearl Harbor, and changed the title to Casablanca in emulation of Algiers, which had been a hit in 1938. Films about World War II were highly sought after now that America was involved in it, and Casablanca had a particularly topical angle: It's about a man who stays out of the conflict until finally his sense of right and wrong compels him to choose a side. Before Dec. 7, 1941, that was much of America's position, too -- and that's why the movie takes place before Pearl Harbor, when Rick's "I stick my neck out for nobody" policy was still acceptable. Audiences wouldn't have liked him if he'd remained neutral even after America entered the war.All of Morocco, including the port city of Casablanca, was under French rule when the war started, and was now run by the French Vichy regime. The Vichy, established after France surrendered to Germany in 1940, basically did whatever the Nazis wanted them to, but officially, Casablanca was unoccupied. In the film, that makes the city appealing for refugees fleeing the Nazis. (In real life, Casablanca wasn't much of a refugee city, though it did serve that purpose for some.) Meanwhile, as the Vichy was licking the Nazis' jackboots, the Free French movement -- le resistance, le underground -- was secretly fighting both groups. So in Casablanca you have your Nazis, your Nazi-collaborating Vichy, your resistance movement, your native Moroccans, and your European refugees trying to get to America. In a hodgepodge like that, you can see the appeal of a position like Rick's, where you run your business, do your thing, and stay out of it. Humphrey Bogart had been busy as a supporting actor in the 1930s, appearing in some 40 films before his back-to-back leading roles in High Sierra and The Maltese Falcon in 1941. Casablanca cemented his new fame, made him viable as a romantic lead despite his short stature and general oiliness, and helped him become the highest-paid actor in the world. The director, Michael Curtiz, had been a filmmaker in his native Hungary, then in Austria, before coming to Hollywood in 1926. He worked quickly and efficiently, often treating actors and subordinates callously, and cranked out solid films like The Adventures of Robin Hood (1938) and Angels with Dirty Faces (1938, in which Bogart co-starred with James Cagney). Casablanca producer Hal B. Wallis -- generally credited as the real creative force behind the film -- was good friends with Curtiz, and hired him to direct when his first choice, William Wyler, was unavailable. Casablanca was scheduled for release in the spring of 1943, but was rushed to premiere in New York on Nov. 26, 1942, to capitalize on the successful Allied invasion of North Africa (including Casablanca) a few weeks earlier. It was released nationally two months later, in January 1943 (this time to coincide with a big meeting between Roosevelt and Churchill in Casablanca), and so even though its premiere was in 1942, it was considered a 1943 release as far as the Oscars were concerned. Forever we must wonder how it would have fared at the Oscars if its competition had been films from 1942 rather than 1943. The movie: In 1941, Rick Blaine (Bogart) runs a classy American-style nightclub in Casablanca -- complete with dining, dancing, and a casino -- while avoiding wartime politics. But then Ilsa (Ingrid Bergman), an ex-lover who broke his heart, shows up in town, trying to make her way to America with her freedom fighter husband and desperately needing Rick's help. What it influenced: I guarantee you've heard quotes from this movie even if you've never seen it. "Here's looking at you, kid" (which was Bogart's own contribution); "I think this is the beginning of a beautiful friendship"; "Round up the usual suspects"; "We'll always have Paris"; "Of all the gin joints in all the towns in all the world, she walks into mine"; "The problems of three little people don't amount to a hill of beans in this crazy world"; "You'll regret it -- maybe not today, maybe not tomorrow, but soon, and for the rest of your life." And, of course, "Play it again, Sam" -- except, whoops, no one ever actually says that in the movie. Ilsa says, "Play it once, Sam, for old times' sake," followed by, "Play it, Sam. Play 'As Time Goes By.'" Later, Rick tells Sam, "You played it for her and you can play it for me," followed by, "If she can stand it, I can! Play it!" But no "play it again, Sam." The song in question, "As Time Goes By" ("You must remember this/A kiss is just a kiss..."), was from a 1931 Broadway musical and also figured into the play Casablanca was based on. So significant is the song to the movie -- and the movie to movie history -- that the logo at the beginning of Warner Bros. films now includes a snippet from the chorus. (If you'd like to sing along, the words are: "The fundamental things apply/As time goes by.") The film got mostly good reviews and performed well at the box office; depending on the source, it was either the sixth or seventh highest-grossing film of 1943. (Ronald Reagan's This Is the Army was No. 1.) Its victories at the Oscars, held in March 1944, boosted its profile, and over time it came to be iconic, especially as Bogart's celebrity increased. Key to the film's popularity at the time was the fact that it had an anti-Axis message but didn't hammer it home. In the words of the Variety review, "Film is splendid anti-Axis propaganda, particularly inasmuch as the propaganda is strictly a by-product of the principal action and contributes to it instead of getting in the way." The New York Times' Bosley Crowther wrote, "It certainly won't make Vichy happy -- but that's just another point for it." Plenty of movies at that time were blatantly rah-rah in their support-the-war themes, and audiences didn't mind too much. But it never hurts to convey the message subtly, surrounded by story that is genuinely entertaining, romantic, suspenseful, and funny. No one has been foolish enough to actually remake Casablanca (though Francois Truffaut was supposedly invited to do so in the 1970s), but plenty of films have borrowed from its story and characters. Bogart reunited with Curtiz and Casablanca co-stars Claude Rains, Sidney Greenstreet, and Peter Lorre in 1944's Passage to Marseille, while two later Bogart films -- To Have and Have Not (1944) and Sirocco (1951 -- have Casablanca-ish plots. The Marx brothers made a parody called A Night in Casablanca (1946); Neil Simon borrowed from it for The Cheap Detective (1978); and the Pamela Anderson starring vehicle Barb Wire (1996) is a futuristic take on it. Films like Caboblanco (1980) and Havana (1990) were clear attempts to recapture the Casablanca magic, to little effect. There were two attempts at turning Casablanca into a TV show -- which, if you can get past the heresy, isn't actually such a bad idea. Both were prequels, set at Rick's cafe before the events of the movie, a setting that surely offered much potential for drama and intrigue. One version aired on ABC in 1955 and lasted five episodes; the other was on NBC in 1983, starred David Soul, Scatman Crothers, and Ray Liotta, and only made it five weeks. What to look for: Watching the film now is very different from watching it in 1943, and not just because you're watching it on DVD instead of paying a nickel to see it at the movie house. Modern viewers see the film through the filter of already knowing how the war turned out (spoiler: we won), but contemporary audiences were still in the middle of it. The theme of everyone making sacrifices to help Good defeat Evil is probably even more stirring when the outcome of the battle being depicted hasn't been determined yet. Casablanca may have seemed like a rallying cry, a reminder that this war -- the one in the movie, which we are also fighting in real life -- must be won. First-time viewers are often surprised at how funny the dialogue is, especially thanks to no-nonsense Humphrey Bogart. There are many terrifically dry exchanges like these:GERMAN OFFICER: What is your nationality?

RICK: I'm a drunkard.UGARTE: You despise me, don't you?

RICK: If I gave you any thought I probably would. UGARTE: Rick, think of all the poor devils who can't meet Renault's price. I get it for them for half. Is that so parasitic?

RICK: I don't mind a parasite. I object to a cut-rate one. CAPT. RENAULT: Carl, see that Major Strasser gets a good table, one close to the ladies.

CARL: I have already given him the best, knowing he is German and would take it anyway. And while the core story is about Rick and Ilsa, they are surrounded by a host of colorful characters. Michael Curtiz didn't have a very distinctive directorial style -- you could watch five of his films in a row and not realize they were by the same guy -- but he did insist that film be a visual medium, so the camera roams around Rick's cafe, giving us an intimate view of all the disparate folks. The street scenes, despite being shot on a Hollywood back lot, have an authentic flair (not least because many of the extras were actual European refugees who had come to California). Dooley Wilson, who played Sam the pianist, was actually a drummer and had no piano skills whatsoever. This is painfully obvious in the scenes where he's supposed to be playing. Veteran cinematographer Arthur Edeson, who'd shot All Quiet on the Western Front (1930), Frankenstein (1931), and The Maltese Falcon, used light and shadows in Casablanca to play up the film-noir elements. We often see shadows in the shapes of crosses or bars, suggesting imprisonment, sacrifice, and the Free French movement (which had the Cross of Lorraine as its symbol). What's the big deal: Citizen Kane is a technical marvel that leaves some viewers cold. Casablanca is the opposite, a warm, beloved film that is unremarkable from a technical standpoint. (In fact, it's loaded with continuity errors, though probably not more than most movies from its era.) There is nothing about the movie that seems to be striving for greatness or importance; it just does its thing, efficiently and competently. But somehow, as if by magic, this ordinary production earned not just respect but outright affection from viewers. Sometimes it's the simple, unobtrusive movies that worm their way into our hearts. Further reading: Here are the original reviews from Variety, the New York Times, and Time magazine. (Time panned it! Blasphemers!) You might also enjoy Roger Ebert's 1996 essay, though he repeats the false legend that Ingrid Bergman didn't how the film was going to end until the last day of shooting. See also Tim Dirks' exhaustive entry at The Film Site. * * * *Eric D. Snider (website) is looking at you, kid. RIGHT NOW.