The quartet enter this unspoilt Eden in a state of harmony - the now-notorious "Duellin' Banjos" sequence, rather than ominous, is actually a rare example of locals and interlopers playing nicely together - before coming to fall badly out of synch with their surroundings; soon, these would-be masters of the universe find themselves on their hands and knees in the dirt, scrabbling and, indeed, squealing for their lives. For yes, this was 1972, and - one whole year before Last Tango in Paris - the film in which sodomy went mainstream, in a scene that predicted the extreme cinema of the late 1990s (John Boorman's direction seeming to stretch out time, and his characters' torments to fit) and serves as payback for what such supposedly civilised folks as Beatty had been doing to the American landscape for years.
If Deliverance still (pardon the pun) holds water today, it's because those waters remain as muddied and troubled as ever. James Dickey's novel and screenplay were devised as parables of the great American divide(s), pertinent to the era of Obama and Fox News as they were to that of Nixon and Vietnam. Assholes weren't the only things being split here: country would be set against city, man against nature, brain vs. brawn, each new conflict revealing further prejudice, and - collectively - measuring just how much disunity there was, and is, within the supposedly United States. Even these four friends can't ever seem to get their stories straight, resulting in a quietly nightmarish coda - a waking dream - that might be understood as as much a coming-home drama as might be found in any 70s war movie: these men left a part of themselves behind up country, which they know they will never be able to talk about, either individually or together amongst themselves.
The overall effect is reliant on Boorman's ability as an outsider to summon up something thoughtful and disquieting alongside the muscular, primal thrills, or - in other words - to reconcile, within a two-hour entertainment, the Reynolds and Voight characters' perspectives, and display markedly greater sympathy for the latter's agonies, which you couldn't ever imagine a Milius or Michael Bay achieving. If not quite up to the hallucinatory force of the same year's Aguirre, Wrath of God (Deliverance's spiritual prologue), it stands as one of the more haunting and beautiful action-adventures Hollywood ever gave us, Vilmos Zsigmond's cinematography hewing close to a nature that was only ever going to win out over this opposition, robust as it was in that 70s character-actor way. For lest we be drawn in by the drama to forget, Boorman's crew were also seeking to impose themselves on their environment - and you can bet the actors, sent hurtling over white-water rapids and down sheer rock faces, had their own stories and scrapes to show for it.
Deliverance screens on ITV1 this Wednesday at 2.45am.