From the vantage of 2015, Francis Ford Coppola’s The Conversation can seem either up-to-the-minute prescient, a relevant commentary on the NSA and our surveillance state, or like some relic of the ancient past, when our privacy is routinely signed away on social media, or with insta-clicks of byzantine “Terms And Conditions” agreements. Either way, it’s fascinating to watch Harry Caul, the surveillance expert played by Gene Hackman, protect his privacy so scrupulously during an era where it’s sacrificed so willingly, or violated so readily. We’re currently living at the end of The Conversation, only without Caul’s instinct to hack through every inch of his apartment looking for bugs. Today, those 21st-century bugs help us find the nearest Starbucks, or cough up meta-data to government anti-terror operations. There’s no escape.

But 40 years ago, such high-tech infringements on private lives were deeply unsettling and relatively new, and The Conversation was the first and perhaps best post-Watergate thriller to feed off that paranoia. (In fact, Coppola claims the timing was accidental: The film was conceived before the break-in, though surely that informed the mood.) The issues of surveillance and rights violations are in play in The Conversation, but Coppola is also interested in teasing out the themes of truth and perception that run through Michelangelo Antonioni’s 1966 benchmark Blowup, its primary inspiration. In Blowup, a fashion photographer inadvertently captures what he believes to be a murder while snapping pictures in the park, but the process of “blowing up” the photographs obscures the truth as much as it reveals anything. Here, the aural information is clearer—a conversation in San Francisco’s Union Square, recorded through multiple mics and cleanly assembled—but a subtle vocal emphasis makes a profound difference. The truth is slipperier than it seems, even when we feel we have it firmly in our grasp.

The masterful opening sequence introduces the rigorous style of the film, which mixes pans, zooms, and mechanical distance of surveillance cameras with Walter Murch’s densely layered soundtrack, which swims in aural ambiguity. The physical space, however, is notably straightforward: In a city full of odd inclines and sharp angles, Union Square, a gathering place in the middle of the business district, stands out for its conservative geometry. That interplay between the muddle of what Caul’s targets (a couple played by Cindy Williams and Frederic Forrest) say and the clear, open space where they say it feeds into the film’s grand design. The operation goes well, and Caul retires to his apartment, which is triple-locked and has a burglar alarm, and which has a phone he almost never uses and claims not to have. The first conversation audiences hear him features him insisting to his landlord that he possess the one and only key to the place.

But no man is an island, and if insidious outside forces don’t get to him first, then his conscience will. Ever the professional, Caul prides himself on doing the job he’s been paid to do—several people confirm he’s the best at it—and not thinking about how his recordings might be used for sinister purposes. But this latest gig troubles him deeply, partly because he’s haunted by a job in New York City that cost the lives of three people, and partly because he’s disturbed by the fearful tone that runs under this Union Square meeting. When he lets a stranger into his life in a moment of personal weakness, his worries are confirmed, and he sets about trying to understand the recording and perhaps put a stop to another tragedy.

The Conversation is a movie of the moment, no question. It’s the first in a series of 1970s thrillers like The Parallax View and Three Days Of The Condor to articulate the creeping paranoia and dread that was gripping the country. But it’s really a much more personal, character-driven piece than that, sharply departing from the more expansive visions of the Godfather movies that bookended it. Like Antonioni, Coppola was wrestling with the properties of his chosen medium and showing how art can conceal and deceive as much as it can tell us something plain and true. Beyond that, though, The Conversation is about the many walls of Harry Caul, who builds a fortress around himself, but can’t stop the barbarians at the gate. All the Catholic guilt and mortal danger that comes crashing down on Michael Corleone in the Godfather movies applies to Caul, too, even though he’s operating with a moral compass that points closer to true north.

Caul’s stance with regard to private surveillance is that he isn’t responsible for anything that happens beyond the parameters of the job, which protects him from knowledge of any unsavory consequences. This is how scientists might rationalize The Manhattan Project or any other pursuits of knowledge that harness the dark forces of nature. But for Caul, it’s a form of self-deceit that cannot be sustained. Before the film even opens, he’s been morally wounded by what happened to him in New York, and there’s no coming back from that, because he knows he helped instigate a triple murder, and he knows such a result in San Francisco would chip away at his soul even further. His visit to a confessional is a desperate, ultimately hapless attempt to gain absolution, but his conscience will not let him off so easily. He cannot do his job, because he ultimately must know how his recordings are being used, even before they’re stolen from him.

As for his private life, Caul protects himself with full knowledge of how people like him might infiltrate his home. He knows from the inside how vulnerable individuals can be to people intent on invading their personal space, just as Edward Snowden knows your Internet passwords are woefully insufficient. But Coppola isn’t making a case for restoring First Amendment privileges with The Conversation, at least not primarily—which is how audiences today might read the story. The scale of the film is ultimately much more intimate than that: Caul’s need to construct these borders around himself would make him a tragic figure even if the “conversation” of the title turned out to be perfectly innocuous. Hackman plays Caul as a sharp, sometimes withering personality who can break down people’s motives as readily as he can deconstruct the latest in flimsy technological gizmos. But he also can’t mask his sadness and alienation, that feeling of otherness, even among colleagues who know the source of his paranoia. It’s part of what makes him the best at what he does—he knows all the tricks and plugs all the holes—but the personal toll is severe.

The Conversation has an unforgettable ending where the walls have finally tumbled around Harry Caul, and he’s playing tenor saxophone in the rubble. His life has been destroyed from within and without, and it’s been done in collaboration with sinister forces, not entirely by them. The moral, emotional, and physical protections he’s carefully installed to operate in San Francisco are untenable; one of the revelations of The Conversation is that Caul is already fatally compromised before the action of the film sets his collapse into motion. The film leaves two impressions: One, similar to other 1970s thrillers, is that Americans have no true privacy and cannot protect themselves from the intrusion of governmental or corporate entities. The other is that no one can live like Harry Caul, without any transparency and without the possibility of true intimacy, and expect to keep their sanity. What happens to him is heartbreaking. He’s the one who ensures it’s inevitable.

The Conversation conversation continues over in the Forum, where Keith and Nathan further kick around the film’s sound editing, use of music, political timing, and more. And on Thursday, Charles Bramesco adds some thoughts on Walter Murch’s sound-editing career. Stay tuned.