Jack Nicholson turned 75 recently, to much slavering from the media. And why not? How many other performers are great actors as well as glorious stars?

If there's a reason Jack Nicholson is an indelible face on the Mount Rushmore of Hollywood, it's his potential to tune performances all the way from 0 to 10 — he is as capable of blending graciously into the scenery as transforming it into a china shop and charging at it with a lusty snort. We've seen him as an ensemble actor, making music with the rest of the orchestra, and we've seen him as a flamboyant solo performer, a star, executing exquisitely hammy variations on that cocked eyebrow and that lascivious leer.

Now that we have some distance from the New Hollywood of the 1970s — it's not that new anymore — there's a case to be mounted that the reason Nicholson wasn't as celebrated as Pacino and De Niro is that he wore his greatness so lightly. He was too cool to let us glimpse the bullets of sweat.

Which film singles out Nicholson at his most actorly? Let's leave aside “One Flew Over the Cuckoo's Nest” — the film that fetched him his first Oscar as well as the film that patented his Jack-isms — and look elsewhere. At “The King of Marvin Gardens”. At “The Last Detail”. At “Chinatown”. And at “Five Easy Pieces”, which is simply one of the saddest films ever made, one of the most empathetic portrayals of anomic rootlessness ever unleashed on screen.

The scene that gets me, every time, is when his character, an oil rig worker named Robert Dupea, is driving to work and is caught in a traffic jam. The irritation is beginning to build. He tries to take the edge off with a swig from Elton's drink, straight from the bottle. And then, a quintessential “Jack” moment, from early in his career. When the driver behind honks unceasingly, he leans out of the window and yells, “Why don't you flash your lights so that we can see what else you got for Christmas?”

Now he's really warming up to playing Jack. He gets out, into the middle of the road, in the midst of the rows of cars, and proclaims, “Why don't we all line up like a goddamn bunch of ants in the most beautiful part of the day and gas ourselves?” A dog in a nearby car barks at him. He barks back. He climbs a pickup truck and leans forward to see how much of the road ahead is blocked. When he turns, he sees a piano — an oasis of beauty in this desert of chaos.

He shoves aside the cover, seats himself, limbers up his arms, and begins to play. We don't hear much of his playing, as the notes are consumed by the angry honking, as if from an experimental Beatles recording session, but that's when we get a sense that this man may not be the oil rigger he says he is, and our suspicions are confirmed as he continues to play even after the truck revs up and takes the exit ramp to someplace that's never named. We just know that he's been playing for a long time, at the back of this truck and in the backstory of his life.

Nicholson gets plenty of opportunity to play close-ups later on, when he moves in, for a while, into his invalid father's home, but this brief scene captures the actor's very essence — the effortless commingling of subtlety and showmanship. Gradually, as fame found him, the showman side asserted itself thumpingly, and we began to see more of the star, most notably in “As Good As It Gets”, surely one of the oddest amalgams of comedy and drama ever attempted. (Do you know another film that forages for fun in a landscape strewn with sickly children, homophobia, racism, neurotic disorder and poverty?)

Favourite scene? When he crashes through his doctor's office and sweeps aside the man's indignation. “How can you diagnose someone as having an obsessive compulsive disorder and then act as if I had some kind of choice about barging in here?” The line is, at once, so funny and sad that it forces us to wonder if there's another actor who could deliver it at just this right temperature. Belated birthday wishes, Mr. Nicholson.