History is factual. History is chronological. History is linear. But memory? Memory is none of those things.

Memory is selective, memory is jumbled, memory travels in different directions. And so does “Mothering Sunday,” Eva Husson’s affecting and visually pleasing — if languorous — meditation on love and loss, based on a woman’s memory of an impactful day that reverberates through her long life.

At first, the leaps between time periods — from the postwar ’20s to the ’40s to the ’80s — can feel jarring. Soon enough, though, Husson makes us understand that this is how memory works, and the rhythm makes sense.

But “Mothering Sunday,” based on the 2016 novella by Graham Swift and deftly adapted by Alice Birch, isn’t just about memory. It’s also about war — namely World War I and the devastation it wrought on countless villages like the English one here, which lost an entire generation of sons.

It’s about love, too, and sex, and also about class — the indelible line that divides our two lovers, played with true intimacy by a fresh-faced and thoughtful Odessa Young and Josh O’Connor, very far from his repressed Prince Charles in “The Crown.” For the bracing intimacy — and the unabashed nudity — one can thank director Husson, who brings her very French, sexually frank approach to the stuffy British upper class..

But perhaps most affectingly, “Mothering Sunday” is about grief, etched indelibly on the faces of parents who’ve lost children. You’ve never seen a sadder or more desperate Colin Firth, as a father who tries to shoo away his grief with hopelessly fake cheer. These efforts do nothing to help Olivia Colman’s Clarrie, his wife, a once-vivacious woman who’s inhabited a bitter shell since the death of their two sons in the trenches. Clarrie has few lines but utters them with a restrained agony you won’t soon forget.

If that couple weren’t enough dream casting, we have none other than Glenda Jackson, playing protagonist Jane Fairchild’s older self, a half-century into the future. But more on that in a moment.

Most of the action takes place in 1924, on a spring day in a pretty village where three families are lifelong friends. Jane (Young), maid of the Niven household, is serving breakfast when she’s offered the day off by her employers (Firth and Colman). It’s Mothering Day — aka Mother’s Day — but Jane is an orphan. So she heads off on a bicycle to tryst with her secret lover, law student Paul Sheringham, the only one of five boys, between the three families, who survived the war.

Their love, of course, is forbidden. Jane even had to witness the engagement of her longtime lover to the daughter of the third family (while serving them all dinner, no less). The wedding is approaching, and on this Sunday, the families are gathering by the river to celebrate. But first, Paul makes passionate love to Jane, then leaves her to explore the large family house naked, a liberating moment that sees her running her fingers along the books in the library — a hint of her future as a writer.

This is no happy luncheon, however, and not just because of a shocking event that will soon transpire. When Godfrey (Firth) tries to make a cheery toast, Colman’s Clarrie erupts, giving harrowing voice to the permanent pain they all feel.

These 1924 scenes are toggled with extensive 1940s-era scenes, with a now older Jane (still Young) who is writing and working in a bookstore. There, she meets her new love, Donald (Sopé Dìrísù), as they connect over philosophy. Sandy Powell’s wonderful costumes transition from meticulously created ’20s dresses to a chic ’40s belted coat that Jane wears with a smart beret.

What we don’t quite get to understand is what kind of a writer Jane is becoming. There’s no voiceover narration, so we only hear a few words here and there, uttered by Jane in dreamlike memories.

This gap becomes even more noticeable in the final chapter, when Jackson graces the screen all too briefly. The elderly Jane has just won a big literary prize. “I’ve won all the prizes,” she says wearily to the waiting press outside, wondering what more there is to say. “Every single one.”

It would be nice to know more about the brilliant writer Jane has become. We do get a lovely visual connection between the two Janes, eyes meeting across the decades. What are they thinking?

As with much of the film, it’s something that looks great, but remains just a bit out of reach.

“Mothering Sunday,” a Sony Pictures Classics release that’s in select theaters beginning Friday, has been rated R by the Motion Picture Association of America “for sexual content, graphic nudity and some language..” Running time: 104 minutes. Two and a half stars out of four.

MPAA definition of R: Restricted. Under 17 not admitted without parent or adult guardian.