There are a million reasons why Stanley Kubrick's "The Shining" has become such a beloved film, but the top of the list has got to be Jack Nicholson's performance as Jack Torrance. Unlike his book counterpart, Nicholson's Jack gives off unsettling vibes from the moment he shows up on screen, and he only gets worse from there. The horrors of the film have less to do with the ghosts inside the hotel; they're more about how terrifying it is to be trapped in a place with a guy who's clearly losing his mind.

To pull it off, Kubrick's team worked with Nicholson to try to figure out the right tone of voice for him to display his mental state to the audience. It was tough to figure out in part because the Jack character doesn't actually talk that much throughout the movie. "The Shining" has lots of long, atmospheric scenes with surprisingly little dialogue, and when Jack does talk his sentences tend to be on the shorter side. As co-writer Diane Johnson put it in a 1997 biography, "Jack Nicholson speaks in short blocks."

Nevertheless, Nicholson still needed to deliver those short lines in a very particular way in order to strike the right tone. "The character had to be a specially demanding verbal combination — intelligent, unpleasant, mordant, and sarcastic," Johnson said.

Talking Up Or Down

Part of figuring out the right voice involved watching a bunch of Nicholson's other movies and studying his various techniques. "In some, he played a 'down' person, measured, slow," Johnson explained. "We decided he was more interesting 'up' — as an active, voluble person, like the role he played in 'One Flew Over the Cuckoo's Nest,' rather than as a contemplative, brooding person."

It's a technique that led to some of the best moments in the whole movie, like the little monologue Jack gives to Wendy when she asks him about his writing. Nicholson is manic in the scene, talking fast and over the top as he hits himself on the head repeatedly. The scene where he asks Wendy to give him the bat is another winner, as the tone he uses straddles the line between funny and terrifying. "I'm not going to hurt you, I'm just going to bash your brains in," is an insane line, but one that's delivered with perfect measure.

Of course, Nicholson's delivery isn't the only thing that sells him as believably going crazy. "The Shining" also takes advantage of the famous Kubrick Stare, where he has the character stare at the camera that's positioned slightly above his eyeline. There's also the haunting score and Shelley Duvall's performance as Jack's increasingly terrified wife. It's hardly Nicholson's only portrayal of an unhinged maniac, but his take on Jack Torrance is definitely one of his best.

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