“Freud’s Last Session” is a period piece about an imagined meeting between the Father of Psychoanalysis Sigmund Freud and an “Oxford don,” the emerging “Christian apologist” who would go on to write “The Chronicles of Narnia,” C.S. Lewis.

Based on a play by Matthew St. Germain, it’ s a thoughtful, literary-minded war of wills and words. The The “godless” rational Viennese Jew challenges the traumatized World War I veteran who’d come home to Oxford, reaffirmed his Christianity as he studied and taught English literature, and compared notes on the mythology and lore of many cultures with some like-minded friends and colleagues, most famously J.R.R. Tolkien.

Anthony Hopkins adds another grand laurel to his much-honored career, giving a grumpy, imperious twinkle to Freud, at the end of his life, lauded the world over and not above insulting the 40 year-old Lewis (Matthew Goode, spot-on as always) to his face.

They gently and sometimes testily spar, a sick old man fretting over the pain from his primitively-treated oral cancer and puzzled about how “someone of your supreme intellect” could “embrace an insidious lie” and not let go of “this fairy tale of faith” told by the Christian Bible.

Lewis counters by suggesting Freud has replaced faith with “sex,” in his theories and writings about understanding the human condition, but leans on every Christian apologist’s favorite comeback when backed into a corner.

“Have you ever considered how terrifying it would be if you’re wrong?”

In Matt Brown’s film — he gave us “The Man Who Knew Infinity” — the well-matched leads go at it in this often uneven battle of wits in what is certainly the most quotable film of the year.

Lewis, already well-known, having published “The Pilgrim’s Regress” and taken a pretty good shot at Freud in it a few years before, makes a reluctant and tardy trek to The Great Freud’s rented house two days after Germany invaded Poland. He’s been summoned.

That’s the jumping off point for their to and fro during a day in which the radio is switched on and off to hear war updates — Britain has given Germany an ultimatum, which the Germans are ignoring. We’ve heard their leader calling for the “anihillation of the Jewish race in Europe” in a radio speech under the opening credits. We will hear actual BBC updates, and British Prime Minister Neville Chamberlain’s response before the day is done.

Brown expands the play, opening it up into the garden, a quick hike to a nearby church as air raid shelter, adding to Freud’s thoughts on Christianity as “art appreciation.” He admires the statuary and stained glass of it all. And we’re treated to vivid Vienna flashbacks for Freud and WWI trench trauma for Lewis.

That gives the film more context and visual variety, adding to the richness of the text and the wonderful actors performing it.

But this “opening up” also makes for some mischief, as it adds Anna Freud (Liv Lisa Fries) and the early years of her lifelong relationship with Dorothy Burlingham (Jodi Balfour) and references Anna’s father’s disapproval. Jeremy Northam (Uncredited?) plays a psychoanalyst suitor to Anna that Sigmund most contend with.

The film also gives credence to the possibility that pioneering childhood psychologist Anna was not just her father’s heir apparent in psychology, his caretaker and pupil, but perhaps something worse, an accusation I can find no credible source to back up.

Is the purpose of this to diminish the already somewhat historically-diminished Freud? Seeing as how the simple existence of this speculative play-turned-film serves to place the “Chronicles of Narnia” children’s fantasy novelist and famous WWII era BBC radio Christian apologist on the same level as Sigmund Freud, that seems a reasonable guess.

But for the viewer, even that just embellishes what is a lovely, poignant thought exercise in the most eloquently argued film of the year.

Rating: PG-13 for thematic material, some bloody/violent images, sexual material and smoking.

Cast: Anthony Hopkins, Matthew Goode, Liv Lisa Fries, Jodi Balfour and Jeremy Northam

Credits: Directed by Matt Brown, scripted by Mark St. Germain and Matt Brown, based on St. Germain’s play. A Sony Pictures Classics release.

Running time: 1:48