NEW YORK — For all its six seasons, “Downton Abbey” has been a graciously paced time-scape through early 1900s Britain.

Home base, of course, was the grand estate that lent the series its name. There the aristocratic Crawley family and their household servants felt the world changing — however incrementally — under their feet.

Spanning from 1912 to the dawn of 1926, “Downton Abbey” was always about change. The Old versus the New. Time-honored values accosted by modernity. Social graces under fire.

What to make of the encroachment of a telephone, or the very idea of a lady out pursuing a career. The changes navigated by the “Downton” denizens provided us viewers, a century removed, with the opportunity to measure ourselves against them as we, too, cope with change that alternately gladdens and confounds us. And as we, too, cut ties with the past.

Now it takes nothing away from this glorious series to recognize that change, and a resistance to changing, has paved the way for the show’s impending end.

“The world is a different place from the way it was, my lord,” says the butler, Carson (Jim Carter), to his boss Robert Crawley, the Earl of Grantham (Hugh Bonneville). Then, with stiff-upper-lip resolve, he adds, “Downton Abbey must change with it.”

Not so with “Downton Abbey” the TV series, which gloried in staying put.

Airing at 9 tonight on PBS’ “Masterpiece,” the conclusion is tender, upbeat and mostly satisfying, with no loose ends, nothing left to doubt, nothing likely to ignite water-cooler debate come Monday morning. This is no head-scratching finale as with “Lost” or “The Sopranos.”

Of course not. Throughout its run, “Downton” always knew what it was, as did its audience, which loved it for its steadfast clarity and sense of purpose.

It was steadfast with savory writing by series creator Julian Fellowes, who authored every script, and with its splendid cast and lush production values.

It was steadfast, too, in its posh confinement to Downton Abbey, where, even as change gradually imposed itself, the narrative refused to change, and — let’s face it — eventually began to feel repetitive. Even at that sprawling country estate (with occasional excursions to London) there was only so much fresh story to tell.

Asked a couple of years ago how long the series might run, executive producer Gareth Neame cited a familiar principle of drama in replying, “There are only seven stories, and I think the challenge with a long-running TV show is to retell those seven stories without anyone noticing. But there could come a time where we’ll be going, ‘What do we do now?”’

“Downton Abbey” may well have reached a what-do-we-do-now point in its told-and-retold cycle of ailments, heartache, duplicity and politesse, plus withering commentary from the Dowager Countess, as played by Maggie Smith (who in the finale weighs in on what makes the English the way they are by observing tartly, “Some say our history. But I blame the weather”).

The show, in short, was proudly tradition-bound, and prevailed to the end as a TV tradition for the faithful fans who watched it every week and, during each offseason, eagerly sought its return.

Bonneville has said the series is “about family — both the literal family and the staff as family. It explores the minutiae of those social structures, the nuances of the system as to whether someone’s in or out.”

We saw ourselves in them all — in or out, elite or commoner, 1-percenters or the 99 percent. We were constantly reminded that now, as way back then, change is willing to spare no one. Everyone feels the hot breath of progress.

Now we are left on our own to face today’s version of progress, a world of upheaval from which we found weekly refuge on “Downton.” And after Sunday we can ponder the parting words from Cora, Countess of Grantham (Elizabeth McGovern) as expressed to her husband: “I think the more adaptable we are, the more chance we have of getting through.”

Part of our delight from “Downton” was following the struggle of “getting through” as waged by those who seemed to have it all. We feasted on how the 1-percenters of that day kept up appearances, however much they seemed to be living on borrowed time.

“Downton Abbey” is smart to bring its saga to a close before it lets more time pass. It has “gotten through” in magnificent fashion, albeit more and more predictably. Now it’s adapting to obligatory change on its own classy terms: by saying goodbye.