Opening Friday (July 21), A Ghost Story gives us almost 90 minutes of Casey Affleck draped in a white sheet. In the media notes to his own film, writer-director David Lowery refers to the “inherent goofiness” of the film’s central image, which keeps the Oscar-winning Affleck concealed, save for two crudely fashioned eyeholes, for almost the entire movie.

Calling the Georgia Straight from Montreal, Lowery admits that by the second day of principal photography, his confidence in such an audacious gamble had evaporated.

“I lost my nerve entirely. It was only because I had everybody there already and because we were in too deep that I persevered and kept digging myself in deeper,” he says with a laugh. “At night, I would call my producer Toby Halbrooks and vent to him and ask him to pull the plug and just basically air all my grievances with my own ideas, and he would just nod and talk me through it. And he, bless his heart, maintained complete faith in the concept. He talked me off many a cliff. That was helpful to have, even though the next morning I’d get back to set and feel terrible again.”

After three weeks of this kind of hell, Lowery used his one day off from production to work up a rough cut of A Ghost Story’s first act. Mercifully, he liked what he saw. Now that it’s done, most critics like what they see, too. Reuniting Affleck and Rooney Mara with their Ain’t Them Bodies Saints director, A Ghost Story offers a sort of metaphysical reworking of the Patrick Swayze–Demi Moore blockbuster Ghost but with Affleck’s silent spook becoming unmoored from space-time.

This allows Lowery to play with some Philip K. Dick–style time slips—including a visit to a Blade Runner–type future—while keeping us rooted in the film’s melancholic present through a figure that is goofy, yes, but also unaccountably moving. It’s one of the gifts of cinema, the director offers, that we can find such inexplicable emotional power in something so comically banal.

“It’s using something very tangible as a vehicle for expressing something 100 percent intangible,” he explains. “And I think another way to talk around it is to comment upon the history of horror films as social and political metaphors, because almost every horror film is about the world we live in at the time it comes out, and it expresses something that we’re unable to express directly, and that’s why horror films are so persistently popular. And while this film isn’t a horror film, it’s doing something similar: it’s taking something that is inexpressibly common to everybody and using a visual metaphor as a vehicle for taking a deep dive right into it.

“There’s something alchemical about cinematic language that I feel is uniquely suited to capturing that meta-ness beyond the mere physical,” he continues, bringing up the comparably daring Thai filmmaker Apichatpong Weerasethakul. “There are scenes in Syndromes and a Century that I can’t quite explain, but they work in a truly profound way. There are shots of, I dunno, factory ductwork in the ceilings that truly feel mysterious. And I don’t know why.”