When I first talked with Jenison, three years ago, in his fully completed fake Delft music room, he was six weeks into the painting, working every afternoon for a couple of hours. He had just completed the checkerboard floor. He thought the technique seemed to be working. But he had another eight months of almost daily work ahead of him. He was proceeding through trial and error, millimeter by millimeter, fiddling with the paint until the edge he saw between the tiny piece of image in his mirror and on his painted picture dissolved and disappeared.

He was rigorous about painting only what he saw in his mirror, rather than referring to a reproduction of the Vermeer. Or to his gobsmacking memory of examining the real thing for 30 minutes on a wall in Buckingham Palace, wearing a surgeon’s binocular magnifiers. “We talked the Queen into showing it to us. I was, ‘Oh my God.’ It’s totally different from the reproductions. It’s more muted and bluish.” The biggest differences were the crazily meticulous details—the silver thread at the bottom of the woman’s skirt, the key ring on the teacher. In terms of detail, “It was goofy what he did on the harpsichord. It was eye-opening, astounding to see. I had no idea. My biggest takeaway was that I was an idiot. There’s so much in it.”

When I talked to him again recently, long after the painting and Teller’s documentary were done, I asked about his learning curve over the 220 hours he spent with brush in hand. “I started with the ceiling beams. They look horrible. I hadn’t thinned the paint. I was worried about how you make a smooth gradient, so my daughter showed me that. My brushstroke did get better. By the time I got to the rug, I knew how to handle the brush. Not that I could sit down and paint anything today without the apparatus. It’d be a piece of shit.”

Jenison still sounds a little surprised at how he has spent so much of the past decade. He believes he fully succeeded in his mission, but being who he is, he’s not exactly doing an end-zone dance. “It’s probably kind of important” is as far as he’ll go. When we first met, he told me he was 80 percent sure Vermeer used an optical apparatus and a procedure something like his own. After he finished his picture, his confidence was up to 90 percent. Lately, after examining a high-resolution scan of the painting provided by Buckingham Palace, he’s 95 percent sure. The most doubt-inducing part of the mystery for him remains how Vermeer kept the trade secret secret. “That’s the killer argument. That’s the best one there is. I’ve got a file of counterarguments to my own theory.”

But his collaborators aren’t fazed at all by the conspiracy-of-silence issue. “How much of history is lost!” Teller says. “We’re not talking about an age where people put things up on the Internet. There are magic tricks whose descriptions don’t exist.” And Jillette is emphatic, as he tends to be: “Tim’s device is Vermeer’s device! I have no doubt. Tim can give you all the doubt you want, but I have none. It’s not the kind of thing you write down! The photo-realistic painters of our time, none of them share their techniques. The Spider-Man people aren’t talking to the Avatar people. When [David] Copperfield and I have lunch, we aren’t giving away absolutely everything.”

The crux of the resistance to the idea that Vermeer invented and used an optical device, beyond technical and historiographic issues, is that it diminishes our sense of Vermeer’s genius. But great artists in every age use clever new tools and technologies. You could give all the digital contraptions Alfonso Cuarón used on Gravity to a hack director and he’d make a crappy movie. Pro Tools software doesn’t turn a mediocre musician into a great one, but great ones depend on it. Chuck Close bases paintings on photographs and uses a mechanical lift to move his enormous canvases around as he works on them. As Jenison says of the history of art, “perspective is an algorithm, a ‘device’” invented in the 15th century to paint more realistic illusions.

“One of the things I learned about the world of art,” Teller says, “is there are people who really want to believe in magic, that artists are supernatural beings—there was some guy who could walk up and do that. But art is work like anything else—concentration, physical pain. Part of the subject of this movie is that a great work of art should seem to have magically sprung like a miracle on the wall. But to get that miracle is an enormous, aggravating pain.” To see Vermeer as “a god” makes him “a discouraging bore,” Teller goes on. But if you think of him as a genius artist and an inventor, he becomes a hero: “Now he can inspire.”

And Tim Jenison—definitely not a great artist, but certainly a great artificer—is inspiring too, whether or not Vermeer used a device like the one Jenison used in Texas. When I ask what new quest he’s on, Jenison says, “I don’t have a current obsession. I’m between obsessions.”