How do you make a movie about Emily Dickinson? How do you capture the inner flame of a woman whose outward life mostly consisted of parlor conversation with her family and quiet hours spent writing poetry in her room? How do you dramatize a life lived almost entirely in the mind — and a death she foretold in poems so devastatingly intimate, it was as if a curtain lifted for her into another world? Well, for starters, you cast Cynthia Nixon.

Terence Davies’ “A Quiet Passion” takes its time getting started; its early scenes, with first a teenage Dickinson (Emma Bell, her performance blending seamlessly into Nixon’s), then with Nixon as the adult poet, feel disarmingly stilted, with the precise formality of the language seeming to create a barrier.

But stick with it, and keep your eyes on Nixon — a still, gentle-voiced presence whose eyes glow like blue embers. Her Emily is outwardly serene, often seeming to smile at a private joke, yet she conveys the sensation of something furious buried deep within. But this is no fragile waif. Just listen to her admonish the editor who published a few of her poems: “Sir,” she says, in tones that could slice paper, “you have altered some of my punctuation.”

Davies, whose previous films — all meticulously beautiful — include “The House of Mirth,” “The Deep Blue Sea” and “Sunset Song,” has made a quiet specialty of an unfashionable genre: the period literary film. “A Quiet Passion” isn’t for everyone; outwardly, not much happens other than watching a woman get older, become more reclusive (“I have become embittered,” she says), struggle with a mysterious illness, and one day die in the bedroom in which she lived much of her life.

But there are moments of astonishing lyricism, particularly that death sequence, in which a nearly feral Dickinson sees — and lets us see — a terrifying, exquisite vision. Nixon, speaking one of Dickinson’s most famous poems in voice-over, conveys a sense of gentle wonder, speaking the words as if they’re just now emerging and yet were always there.

Because I could not stop for Death

He kindly stopped for me

The Carriage held but just Ourselves

And Immortality

Exclusive: Angelika Dallas; Angelika Plano; opens June 2 at the Modern Art Museum of Fort Worth