When Daniel Day-Lewis, the greatest screen actor of his generation, announced this week that he would be retiring from acting, I had the same initial thought that, I assume, most everyone else did. After a few befuddled seconds of “Why?” I prayed that his announcement wasn’t the euphemism for a health crisis. Once I decided that it probably wasn’t (this is, after all, the actor who took an open-ended sabbatical to build furniture), a conviction began to settle over me. While I had no clear idea why an artist as passionate and celebrated as Daniel Day-Lewis would want to cut his ties to acting (I was going to add “when he’s at the top of his game,” though when has Daniel Day-Lewis not been at the top of his game?), every bone in my body told me that he’d be back. At some point. In some eccentric Daniel Day-Lewis fashion. He’s 60 years old, which really is the new 50, and assuming he lives a long and vital life, how could he stay away? My instinct says that his instinct wouldn’t let him.

It seems more than likely that Day-Lewis will, at some point, want to act again because that’s such a dominating dimension of who he is. Besides, to put it in terms he’d surely disdain: What else is Daniel Day-Lewis going to do? He lives in a tiny Connecticut village and spends much of his time on his 50-acre estate in the remote Irish mountains of County Wicklow, where his twin passions are making shoes and woodworking, plus riding his motorbike through the woods. His youngest son, Cashel, is 15. Does Day-Lewis even have Netflix? Maybe so, but you get the feeling that his idea of binge-watching would be to read all of Dickens’ novels in a single season.

Given the studied sedateness of his lifestyle, which seems organized to balance out his more mercurial side (the side that was convinced he was glimpsing his father’s ghost onstage when he played Hamlet), it’s easy to imagine Day-Lewis busting out of his retirement in about four years by showing up, seemingly out of nowhere, to portray Big Daddy in a stage production of “Cat on a Hot Tin Roof” mounted in some tiny 180-seat theater in Dublin. It would immediately become the hottest ticket in the world. Then, of course, there are the film directors who will likely never stop beckoning.

Paul Thomas Anderson, who guided Day-Lewis to his most perversely beloved performance, as the sociopathic oil baron who stole John Huston’s voice in “There Will Be Blood,” has now bequeathed him his official final role. In Anderson’s upcoming Christmas release, “Phantom Thread,” Day-Lewis stars as the visionary British fashion designer Charles James, who was one of the most influential couturiers of the 20th century — and who, interestingly enough, retired himself in 1958, at the age of 52, 20 years before his death. Given Day-Lewis’ legendary immersion in the roles he plays (during the shooting of “Lincoln,” he never broke character, insisting that everyone on set, including director Steven Spielberg, address him as “Mr. President”), one has to wonder whether he might have developed an obsessive identification with a designer/artist like James, to the point of wanting to echo the way he exited the fashion world at the height of his powers.

Ever since “The Boxer,” in 1997, Day-Lewis has been the Stanley Kubrick of actors, making a major film just once every five years. P.T. Anderson has his own Kubrick-of-Gen-X cachet (he spaces his projects out, heightening their event status, and some of his films are as enigmatic as monoliths), which is part of what the two now share: a talent for the momentous. One could easily envision Anderson, at some point in the 2020s, wooing Day-Lewis back to the big screen by making him the offer of a role he couldn’t refuse.

But enough idle speculation. Five days after Day-Lewis’ teasingly oblique announcement, what strikes me most is that whether he ends up keeping to his pledge to retire or reneging on it (the way that artists from David Bowie to Steven Soderbergh have done), his retirement has a resonance, one that reaches beyond Day-Lewis himself. Will we ever see another actor as brilliant and audacious? Of course. But will we ever see another great actor who is like Daniel Day-Lewis? Maybe not. What retired on Tuesday is something that’s waning in the culture: the belief in acting as a highly sculpted soul transplant — as the mystical spirit of inhabitation.

There are two towering traditions of acting in the 20th century, each represented by a single mythological name. The first name is Laurence Olivier. For a long time, he was seen as the quintessence of virtuosity for the way that he built his characters from the outside in, manipulating his look, his voice, his posture, his gestures. Playing his own face and body like a Stradivarius, he was a genius chameleon who seemed, from role to role, to alter his very being.

The other name is Marlon Brando. Born one generation after Olivier, he was our bard of the Method, of confessional spontaneous expression. The Brando revolution stood apart from — and transcended — the Olivier-identified magic trick of personality manipulation. Yes, Brando sometimes did that too, and brilliantly (a part of him was still a classicist), yet the essence of his genius is that he harnessed the power of pure being. That’s why we exalt the brooding animal magnetism of his performances in “A Streetcar Named Desire” or “On the Waterfront” or “Last Tango in Paris” over his makeup-and-accent performances in films like “Mutiny on the Bounty” or “Viva Zapata!” or “The Young Lions.” (The one movie, famously, where he changed his personality and retained that same underlying raw power was “The Godfather.”) It’s not as if Olivier didn’t have his own animal moments (just think of him in “Wuthering Heights” or “Marathon Man”), but these two define the dialectical poles of modern acting. One was exterior, the other was interior.

Most of the great actors who came afterward, like Robert De Niro or Jack Nicholson, were heirs to the Brando revolution. A few, like Meryl Streep or Ben Kingsley, reached back to the Olivier tradition. But from the moment that Daniel Day-Lewis wowed the world by appearing, in one year, as the scolding Edwardian fop of “A Room with a View” and the loose-limbed gay punk of “My Beautiful Laundrette,” he was always seismically both: an actor of Brandoesque ferocity who fused that quality with the devotion to sheer otherness of an Olivier. That’s why his borderline loopy immersion process is so integral to who he is: It’s doing what Olivier did — becoming another person — brought off with Brando’s wild-dog existential intensity. Just think of him in “My Left Foot” (still, perhaps, his greatest performance), where he works, with soul-shattering power, from the outside in and the inside out.

Yet you have to wonder if the Daniel Day-Lewis ideal isn’t now on the wane. Simply put: Do actors still have a primal passion to be shape-shifters? Occasionally, yes (think Natalie Portman in “Jackie”). The one who always seemed to share the depth of Day-Lewis’ impulses was Heath Ledger, another immersive chameleon who, in “The Dark Knight,” was like a sickie-psychotic Brando. Yet it seems as if the new model for how to act in movies is, essentially, to show up.

It’s certainly possible to give a highly nuanced performance without altering the basic DNA of your personality. There are plenty of inspired actors, from Denzel Washington to Ryan Gosling to Jennifer Lawrence to Jonah Hill, who regularly do just that. They’re working in the tradition of vintage Hollywood, where stars like Hepburn and Tracy and Bogart and Bergman didn’t tend to vary themselves all that much. That’s fine: What they did — who they were — was magical. But Daniel Day-Lewis incarnates something else. For 30 years, he has swung for the fences. He didn’t just want to show up in a movie as some version of himself; he wanted to transcend himself — to literally make acting into an out-of-body experience. The question going forward isn’t whether Day-Lewis is really retiring. It’s whether the spirit of transformation that he represents has come to seem like a mountain that actors no longer need, or even want, to climb.