Self-portraits trick us by exploiting a basic human reaction. When we meet other people we immediately try to judge their inner selves from their facial expressions. Cruel or kind? Intelligent or stupid? Approachable or touchy? When we look at self-portraits we do the same, but it makes no sense, for we are just looking at paint.

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At the end of this beautiful and intriguing book Laura Cumming acknowledges that a self-portrait can only be an illusion. Yet, she insists, the illusion always carries a truth, the truth of how the artist hoped to be seen, and she pursues this idea through a series of brilliantly acute case studies, some chapter-length, some crisped to a few sentences.

She is not in thrall to any overarching theory, so the questions she asks remain cogent, real and often unanswerable. Van Eyck, the earliest self-portraitist she investigates, may not have been one at all. There is no proof his Portrait of a Man in the National Gallery is him. He painted a tiny reflection of himself in a mirror in the Arnolfini portrait, and another in St George’s shiny armour in a Madonna and Child in Bruges. Perhaps these indistinct splodges imply he did not want to choose a face to face the world, as self-portraitists must.

The faces they choose can be puzzling. Why does Botticelli glance at us with such cold disdain from the edge of the crowd in his Adoration of the Magi? Why, in his ­Taking of Christ, does Caravaggio depict himself as the ­figure holding up a lantern while Judas kisses Jesus and the soldiers close in? Is he somehow complicit with the persecutors? Why does Van Dyck paint himself accompanied by a gigantic sunflower, the kind of relationship you might expect in a Salvador Dali? Is it demeaning that, in Las Meninas, Velazquez should be so keen to show himself hobnobbing with members of the Spanish royal household, and display on his breast the emblem of knighthood he had angled for so cravenly?

Cumming tackles questions of this kind, and is intrigued, too, by serial self-portraitists, who avoid choosing a single face at the risk of losing identity altogether. In Rembrandt’s more than 80 self-portraits the shape of the nose, the colour of the eyes and the distance between them change from picture to picture, and the fantastic costumes seem intent on establishing a new self each time. Yet each picture convinces you that it is the truth. ­Perhaps, Cumming suggests, Rembrandt is teaching us that the self is not a stable thing but alters from day to day, and perhaps the theatrical costumes signal a recognition that we experience our lives as performance.

The big contrast with Rembrandt in her account is Dürer. Whereas Rembrandt draws us into a warm circle of shared humanity, Dürer excludes us. He poses, cold and ­perfect, in the 1493 self-portrait, when he was 22, and five years later in the Self-Portrait with Gloves. The first Cumming sees as “expressionless… as a study of cowslips”; the second, as all about social standing, money and lavish dress, “the picturing of oneself as a work of art”. Both approach narcissism, always a self-portraitist’s temptation (and one that Michelangelo violently avoided by painting a flayed human skin, emptied of self, as his own self-portrait in his Last Judgment). Narcissism, or maybe blasphemy, are at issue in the picture ­Cumming selects for her book’s cover, Dürer’s self-portrait of 1500 in Munich, which seems to depict him as Jesus, and which became the face of Christ for future German artists. It is a picture that, Cumming tells us, has been kissed, worshipped and carried through the streets as an icon. In 1905 its relentlessly ­challenging gaze proved too much for one visitor to the Alte Pinakothek who tried to poke out its eyes with a hatpin (luckily it did not penetrate the Renaissance varnish).

The eye-to-eye reciprocity of self-portraits is another of their deceits, for we think the artist is looking at us when he is really ­looking at himself in a mirror. Cumming takes us through the history of mirrors, noting that in the 16th century flat ones were prohibitively expensive so artists, like barbers, had to make do with convex ones. Parmigianino wittily painted his self-portrait on a wooden ­hemisphere, precisely reproducing a convex mirror’s distortions. Vuillard, contrarily, uses a mirror to escape himself. His Self-Portrait in a Mirror with a Bamboo Frame painstakingly records the mirror, but blanks out his own eyes. For Bonnard the mirror is entrapment. His agonised self-portraits all show him as its reflection, never free of its surface. In Norman Rockwell’s Triple Self-Portrait the artist peers round the edge of his canvas, with its jaunty, upbeat likeness, at the blank, bespectacled face that actually meets him in the mirror. The fun and sadness remind Cumming of Rockwell’s comment to his youngest son: “I’d like for someone to tell me that they think Picasso is good, and that I am too.”

Self-portraits that avoid eye contact have their own points to make. Titian, powerfully self-absorbed, gazes abstractedly at the ­middle distance. Goya, in the etching ­prefaced to his chamber-of-horrors Los Caprichos, flicks a sideways glance, as if too pained to meet our gaze. Artemisia Gentileschi, in the first self-portrait by a woman to become internationally famous, labours at a canvas, too busy to spare us a look.

The goons in Cumming’s collection are the egotists, skewered by their own vanity. Sir Joshua Reynolds, in the doctoral robes of Oxford university, poses beside a bust of Michelangelo. Gustave Courbet labours to discover yet another facet of his genius to celebrate. A subsection of self-aggrandisement is self-pity. Edvard Munch’s Self-Portrait in Hell shows him engulfed in flames and looking distinctly anxious, as if waiting for the last tram. He had been through an unhappy love affair with a woman called Tulla Larsen, and when she wanted to marry him he took fright and shot himself, but only damaged the tip of his ­middle finger. The flames of hell are meant to show how upsetting it all was. Tracey Emin is another of Cumming’s chronic self-pitiers, as is Egon Schiele, who portrayed himself as Saint Sebastian in a hail of arrows (though the design is so dazzling that you forget the self-pity, which is clearly just camped-up anyway). Cumming contrasts them all with Van Gogh who, despite his torments, never stoops to self-pity, but paints himself solemn and resolute, triumphing over life’s miseries.

Paradoxically, though Cumming’s book is stacked with visual masterpieces, it is her writing that most claims admiration. She notices every detail in a painting, the way a carpet folds, the varying textures in a dog’s fur, and registers them with a poet’s ­precision. After a time you find yourself poring over the illustrations, trying to guess what she will say about them, and finding, when you read on, that what she says is always ­better than you could have imagined. She does not waste time on evaluation, since we can all do that for ourselves, and she does not parade her opinions. Instead she relies on keen observation, linguistic power and lots of knowledge. It adds up to the most enjoyable art book I have read for years.

A Face to the World by Laura Cumming
HarperPress £30 pp310

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