One reason advance word on the French period drama Portrait of a Lady on Fire has been so thunderous is surely that the themes it wholeheartedly embraces are so vast: it spends its two hours considering nothing less than life, love and the very act of creation itself. On paper, that would indicate some departure from writer-director Céline Sciamma's previous films, which - though not without memorably expressionistic flourishes, like the all-girl hotel room singalong to Rihanna's "Diamonds" in 2014's Girlhood - were principally exercises in quiet, attentive observation. Portrait unfolds over a bigger canvas, it's true - its ravishing images are by Claire Mathon, the cinematographer who did so much to carry the Netflix-bought Atlantics around the world last year - yet it proves strikingly simple, often sparse in its framing, Sciamma remaining disciplined in the way she directs the viewer's gaze, and schools us in what to be looking out for. The film is, on some level, a mystery, describing the genesis of a painting hauled into an art class taught by the mournful Marianne (Noémie Merlant). "What's it called?," asks one student. "Portrait of a Lady on Fire," comes the loaded response, at which point - barely three minutes in - the representatives of that US society who show up for movies just to hear the title being spoken will stand up, applaud and make their exit. Their loss. Beneath the opening credits, we've already seen the students making their first, tentative marks, attempting to capture something of what's made Marianne so melancholy. The assignment is taken up by Sciamma herself when the film enters flashback mode: having set out the framework, she now begins - in the grand melodramatic tradition - to fill it and us in.
The story proper begins with solitude: we see a lighter, forward-facing Marianne, the daughter of a celebrated painter, arriving by boat on an island off the coast of Brittany, where she is to complete a portrait for a well-to-do Italian family. (One early, especially blissful sight: a nude Merlant smoking a pipe while drying herself and her sea-soaked canvasses off in front of the fireplace.) She is, however, adrift without a subject, and this she finds in the family's daughter Heloïse (Adèle Haenel), an imperious former novitiate withheld from us for a good twenty minutes, then introduced emerging from a cape while threatening to throw herself off a cliff. Factor in the girls' conversational icebreaker - mutterings of a recent plummet in the vicinity - and it becomes clear there isn't a melodramatic trope Sciamma won't sweep up and run away with. The portrait Marianne has been commissioned to paint is meant to alert a potential suitor to Heloïse's beauty; it's as if the painter has been summoned here to provide an especially labour-intensive Tinder pic. Yet Sciamma's suggestive imagery tips us the wink to the growing attraction between Marianne and her subject: an interplay of faces as they stand on that cliff edge - looking out to sea, wondering if they, too, might take some kind of plunge - is rather like if Bergman had employed Yves Klein as a cinematographer and turned that famously gloomy gaze outwards, in the direction of pleasure and joy rather than guilt and remorse. The very fact Merlant and Haenel look at one another as spoons must look at tiramisu makes it plain these two are meant to be together; no canvas can possibly separate them for long.
Portrait is as interested in the act of creation as, say, La Belle Noiseuse or The Quince Tree Sun, that (literal) art cinema the 39-year-old Sciamma might well have been raised on: there are longish sequences of Marianne (or Merlant's hand double) scratching away at her easel, which offer the always vaguely perverse pleasure of actually watching paint dry. Where this filmmaker differentiates herself - and where Portrait of a Lady on Fire soars above and beyond its predecessors - is that she's every bit as alert to the world beyond the workshop, and how the artist comes not just to find but to know her muse. In Sciamma's eyes, this isn't just a matter of looking, but loving and empathising; it's not drilling a hole through somebody (as the male gaze has traditionally been accused of doing), but rather noticing who someone might be, the way they hold themselves, and then what that might communicate to any third-party observer about the kind of person the observed was and is. When first completed, Marianne's portrait bears only a superficial likeness to Heloïse (as it does to Haenel); the more time she spends on the island, the more time she gets to know the other woman, the more the painting gains in depth, texture and shade. In her own way, with a few deft brushstrokes here and there, and none of the fuss-and-nonsense that greeted the arrival of the Dogme movement, Sciamma appears to be pasting up a manifesto for her own cinema, and anybody else who might want to commit to it: it states that art means getting to know somebody and passing that knowledge along, and that it must be shaped by both the act of observation and the act of collaboration. It must be consensual; it cannot be a one-way street, nor undertaken in isolation. As those noted art historians the New Radicals put it: we only get what we give.
Perhaps that makes Portrait sound self-indulgent or drily theoretical. Nothing could be further from the truth. That has much to do with the joltingly modern leads, who bring figures from dusty daguerrotypes into full colour as longing, thirsty, flesh-and-blood creatures; Marianne and Heloïse come together to complete this one project, and wind up with one another's faces, bodies and beings imprinted on their very psyches. With their blonde and brunette hair and tutti-frutti red-green dresses, this pair complement one another perfectly, and Sciamma situates them at the centre of a universe that feels as immersive as any Fragonard tableau. She achieves this by keeping those images simple and resonant - never cluttering the frame with period excess - and instead layering up her story. Her ladies gain a surrogate child in the family's maid (Luana Bajrami) - another blank canvas, a girl who needs instruction in the ins and outs of menstruation and needlepoint - and the closer the portrait nears to completion, there's a growing fear that that suitor will show up to whisk Heloïse away. It was some while before I noticed Portrait was a vision of a world without men, hushed, unhurried, and open to the elements; indeed, faced with the thunderousness of the initial critical responses, one shock is the quiet utopia of the film itself. There's an impromptu musical interlude, but set Portrait against the agonised cacophony of the cinema's last notable creation-about-creation, Darren Aronofsky's mother!, and it could be a movie from another planet. If you'll permit me to do anything as noisy as clearing my throat, I think Sciamma gives us one scene too many - she attains perfection, then goes past it - though I can appreciate it might be crucial to her overall design that both her ladies on fire experience some form of catharsis. Otherwise, the established harmony between watchers and watched struck me as entirely legitimate: that one reason the film has been so thunderously well-received is that its effects are thunderously well achieved. Sometimes, if we're lucky, art speaks to us on a profound, maybe even life-changing level. Sometimes our hearts beat loud and in synch.
Portrait of a Lady on Fire opens in selected cinemas from Friday.