Three: that’s the magic number. Trilogies are where it’s at for any world-class filmmaker—think of Satyajit Ray (the Apu trilogy), Krzysztof Kieślowski (the Three Colours films), Lars von Trier (the Golden Heart series: Breaking the Waves, The Idiots, Dancer in the Dark) or Lindsay Anderson’s three films starring Malcolm McDowell as rebellious-schoolboy-turned-coffee-salesman-turned-investigative-reporter Mick Travis (in If…, O Lucky Man! and Brittania Hospital). One film? Anyone can do that. A set of two? They’re just bookends. But three is weighty, commanding, a force to be reckoned with. It’s the Father, the Son and the Holy Spirit. “Diptych” just sounds silly. “Triptych”? You could hang that baby in the Met.
My thoughts turn to this subject because of the release in the UK of Paradise: Love, the first part of Ulrich Seidl’s Paradise trilogy. Each film is devoted to the search for happiness and fulfilment by a different woman in the same family: Paradise: Love  is about sex tourism, Paradise: Faith (which opens next month) concerns religious fanaticism and Paradise: Hope (released in August) takes place at a teenage diet camp. The three films interconnect in small but significant ways; seeing them all in one sitting—as you can do at various cinemas on Sunday 16 June (the Bristol Watershed and four London venues: BFI Southbank, Curzon Renoir, Rio Dalston and the ICA)—helps to highlight those echoes and overlaps. It will also be emotionally exhausting, but that goes for most great cinema.
And next week we’ll see Before Midnight , the concluding chapter in Richard Linklater’s romantic-realist Before trilogy. I’ll be looking at the impact of these wise, intimate films in this week’s NS; I notice also that some cinemas are screening double-bills of the previous two, Before Sunrise and Before Sunset, in the next few weeks. They remain essential viewing, and peculiar among trilogies for having such a long gap (nine years) between each segment. But that has only contributed to their value, their weight: the intervening years have enabled each film to mature. Watching them now together is a revealing experience—you can see Ethan Hawke shed his puppy fat and grow wolfish teeth; you can marvel at how Julie Delpy gets looser and funnier with age.
The rule with trilogies, for me at least, is that they have to be made by the same director (which disqualifies, say, the post-Manhunter Hannibal Lecter movies, even though they all star Anthony Hopkins). Also, their trilogy status should ideally not be applied retrospectively. There doesn’t have to be an explicit link between characters or even themes. Next month, for example, brings the release of the last part of the more informal “Cornetto” trilogy—Edgar Wright’s The World’s End , which follows the same director’s Shaun of the Dead and Hot Fuzz. All three star the same lead actors (Simon Pegg—who also co-wrote the movies with Wright—and Nick Frost) and feature a scene in which someone buys a Cornetto. Beyond that, there is Wright’s spirited genre-busting to unite them. A trilogy united by tone and sensibility is still a trilogy.
But will the emergence of more Cornetto flavours to follow the original ones (strawberry, vanilla, mint choc chip) around which the trilogy was conceived mean that the series will now extend beyond its natural life? If so, the films need to be better than the new Cornettos. I tried popcorn-and-salted-caramel flavour the other day. It was bloody disgusting.
Paradise: Love opens on Friday, Before Midnight on 21 June, The World’s End on 19 July.