IV bis. Case studies: four faces in close-up

Voltaire (1735; versions in Saint-Quentin, Stockholm and elsewhere). The founding image. Voltaire at forty-one, wigged and lit, the mouth's corners lifted a millimetre past courtesy into irony: the portrait defines the La Tour smile and its mechanics — the expression built not in the mouth alone but in the co-ordination of mouth-corner, cheek-muscle and the moisture of the lower eyelid, the whole face agreeing to be amused. Voltaire liked and multiplied it (versions, copies, engravings by the dozen; the philosophe understood image-management two centuries early), and its diffusion made both men: Europe's idea of esprit wears this face. Set beside Houdon's later marble grin, it is the smile's youth — wit still worldly, not yet monumental.

Gabriel Bernard de Rieux (1739–1741; Getty Museum). The machine at full stretch: the parliamentary president life-size in his study, robed, at his papers, among globe, screen and books — pastel doing everything Rigaud's oil did for the last age, and adding its own present tense: the magistrate looks up as if we had entered with a question. Technically a summit (the sheets joined invisibly; the black robe a lesson in dead-colour made living; the still-life passages — glass, paper, gilt — pastel's answer to Chardin), it announced that the medium had no ceiling; commercially it announced the same of the artist. The Getty's acquisition in the twentieth century carried the grand La Tour to America, where it remains the hemisphere's best evidence of what the Salon crowds gasped at.

Madame de Pompadour (1749–1755; Louvre). The essay has told the making; stand now at the result. The marquise sits in full length among her attributes — Encyclopédie, Montesquieu, Voltaire's epic, the music in her hands — and the first surprise, before scale or program, is the address: amid the manifesto, the face does the small human thing La Tour's faces do — turns, attends, prepares to speak. The second surprise is the head's paper, visibly distinct (the face was worked separately and mounted — practical prudence with a busy sitter, and a built-in allegory: the person detachable from the apparatus). Contemporaries read the politics — the mistress as minister of enlightenment; modern eyes add the melancholy: five years of labour, a friendship of sorts between artist and sitter, and beneath the program a tired, intelligent, mortal face (she died at forty-two, nine years on). It is the eighteenth century's fullest portrait of power held by intellect — and it is made of dust.

Marie Fel (préparation, Saint-Quentin). Nine inches of paper; a turbaned head turned over a shoulder; the beginning of a smile that has been beginning since 1757. The préparation of the singer is the fonds' darling and the counter-thesis to everything above: no costume, no program, no Salon — the face alone, seized at conversation's speed by the man who loved its owner. Every account of the modern La Tour revival dwells on it; painters copy it; the museum sells its postcard by the thousand; and its fame states the taste this essay has traced — that the age of the machines is over and the age of the notation is here. The just view keeps both: the Pompadour is what pastel could be made to do; the Fel is what it was — breath, caught. Between the two, the whole artist.

Practicum: how to look at a pastel

La Tour rewards protocol even more than most, since the medium punishes casual viewing (glass, glare, crowds) and rewards patience extravagantly. First, position: find the angle where the glazing stops mirroring the room — usually oblique, close, at the frame's shadow side; the powder-surface only exists un-reflected. Second, distance: begin at conversation's range — the works are calibrated to it; the address only fires at the distance a sitter and painter actually kept. Read the face's centre first — eyes, then mouth — and let the periphery blur as it was designed to: the focusing of stroke from fused features to open costume is the medium's depth-of-field, and it teaches where to look by how it is made. Third, close up (nose to glass, guards permitting): the strokes themselves — hatchings crossing on the cheek, the single dragged white of the eye's light, blue paper breathing through everywhere — the whole fabric alive and provisional, dust standing at attention. Fourth, the préparations, wherever the museum shows them: read them after the finished works, and feel the scaffolding fall away. Last, the room entire: La Tours hang in company (Paris, Saint-Quentin, Geneva), and the ensemble is the point — raise your eyes and let the gallery do what this essay began by describing: a century's dinner party, paused mid-sentence, resuming the moment you turn to go.

V. The smile, examined: physiognomy and the social art

What, exactly, did La Tour catch? The question has a real intellectual history, and the essay owes it a chapter, because his art sits at the centre of the eighteenth century's deepest change in the human face.

Historians of the emotions have documented the shift: the French seventeenth century did not smile in portraits — the open mouth belonged to peasants, drunkards and genre painting; dignity was closed lips and command. Across the eighteenth century the closed face opened. The culture of the salons made conversation the supreme social art; sensibility made responsiveness a virtue; dentistry (the historians insist, correctly) made teeth showable; and the portrait's task migrated from station to presence — from what a sitter was to how a sitter was with you. La Tour is this revolution's chief executive. His invariable format — close, bust-length, the body turned, the face returning to the viewer, the mouth at the first instant of speech or the last instant of listening — is a machine for one effect: address. The sitter attends to us; the portrait's space is conversational space; and the famous smiles are precisely calibrated social smiles — wit's smile on Voltaire, patronage's on Pompadour, integrity's plain version on Rousseau — a taxonomy of Enlightenment sociability, drawn from life at talking distance.

His own account of the practice, recorded by early biographers, is the century's best sentence on portraiture: sitters think they sit for their features, he said, but 'unknown to them, I descend into the depths of them and carry away the whole' — je descends au fond d'eux-mêmes et je les remporte tout entiers. The claim is grand; the method behind it was empirical: the ceaseless studio conversation was diagnostic, the préparations its lab notes, and the finished works arguments — each face a thesis about a temperament, stated in the set of the mouth and the exact moisture of the eyes. The age's sciences of the face (physiognomy before Lavater systematised it) hover nearby, but La Tour is better than the pseudo-science he anticipates: he reads not fixed character in bone but disposition in motion — what this person is like to talk to — which is why his gallery feels less like a portrait wing than like a dinner party of the dead, still in progress.

Criticism has added its reservations, and honesty records them. The address can shade into performance: some La Tours smile at us as a profession; beside a Chardin (whose few late pastels of himself and his wife, done in La Tour's shadow, are the medium's profoundest works to many eyes), La Tour's brilliance can look — the word recurs from Diderot to now — social, surface's triumph. The défense is in the préparations and the late sheets, where the address drops and something unguarded looks out; and it is in the historical point this chapter has argued: the surface WAS the subject. The Enlightenment believed conversation could civilise the world; La Tour painted that belief, face by face, at its own chosen depth — and when the Revolution burned the salons, his art's world ended with it, which is the next chapter's story.