In 1942, Hollywood churned out over 500 movies, most of which, naturally enough, you will have never heard of (unless you happen to be a professor of Film Studies specialising in the forties, which is unlikely). When they were making Casablanca in that year, nobody was thinking that this was going to be the movie that would become an enduring classic still appearing near the top of “greatest ever movie” polls eighty years later. What makes Casablanca so great?

You already know the synopsis: it’s set in 1941 in Vichy-controlled Casablanca just before Pearl Harbor and America is stalling about entering the war. The Germans’ hold is tightening, and everyone’s fates are uncertain. Everybody is wanting to get out before it’s too late. Against this backdrop, American ex-patriate Rick Blaine (Humphrey Bogart) runs a nightclub and gambling den, Rick’s Café Américain. He also has previous as a fighter in the Spanish Civil War, so he’s no slouch, and he knows a lot of people. He has also come by two “letters of transit”, valuable and authentic documentation that would allow the bearers to make their escape through German-occupied Europe.

Rick’s former lover, from when they met in Paris during the fall of France, Isla Lund (Ingrid Bergman), walks into his club. Her husband Victor Laszlo is a linchpin in the Czech resistance; they need those documents to escape to America and continue his work. When Isla confesses that she still loves Rick (she’s no hussy though: when they’d met in Paris she had thought her husband dead) we come to the nub: Rick’s moral dilemma is to decide between his love for Isla and the good of the world. He makes the right choice, and at the end of the film (surely this is no spoiler) sends Isla and Laszlo off, with their papers, to fight the good fight.

Let’s talk cinematography; it’s full-on film noir by Michael Curtiz. The use of light and shadow is used to dramatic effect: the morally torn Rick is often seen half in light, half in shadow. Laszlo, the bright hope for the future, is almost always in full light. Isla’s flawless and pearlescent skin is accompanied by eyes sparkling impossibly by the use of tiny lights. The venetian blind is a handy way to cast prison bar-like shadows on the protagonists.

The narrative is economical; there is no detail that doesn’t matter to the plot, no scene that is wasted. Sure, there’s corn (more corn than Kansas and Iowa combined, said its screenwriter Julius Epstein) but it’s Hollywood, what do you expect? And surely it’s no coincidence that so many classic lines were thus spawned: “Here’s looking at you, kid”, “We’ll always have Paris”, “Of all the gin joints in all the towns in all the world, she walks into mine”. I know that you already know that the line “Play it again, Sam” was never actually said, so we needn’t mention that!

But let’s look at that closing scene when Rick sucks up his personal loss and delivers that classic parting speech to Isla, to the emotional orchestral accompaniment of As Time Goes By. It is pretty marvellous stuff, isn’t it?