Leonardo as you’ll never see him again

Art history claims few instances in which the insights of a single mind and eye – Rembrandt, Monet, Picasso – shift the paradigm of pictorial possibilities. When Leonardo da Vinci joined the service of Ludovico Sforza in the 1480s, he painted his patron’s mistress, his wife, and a young man who may have been a courtly relation, and transformed portraiture from the rigidly statuesque into something breathing, thinking, moving: an art that dared suggest it could make living people immortal.

At the same time Leonardo painted sacred subjects with such insight into the human that they seem naturalistic yet with a spiritual sense that makes them appear touched with the divine. Individual genius here met a cultural transition – religious power still imbuing the secular world, even as it is ceding influence to it – in a moment that could not be repeated. Leonardo’s contemporaries instantly recognised his quixotic, uncanny brilliance.

It has been celebrated ever since but so rare, fragile and totemic are Leonardo’s surviving paintings – just 15 are securely attributed – that it has until now proved impossible to organise an exhibition demonstrating work by work his range, depth and development as a painter. The National Gallery’s gathering of eight paintings borrowed from Paris, Krakow, St Petersburg, Milan, Rome, plus scores of important drawings, in Leonardo da Vinci: Painter at the Court of Milan is, therefore, a triumph of diplomacy and enlightened scholarship. It is the most notable Old Master show this century and certainly its coup in reuniting London’s “The Virgin of the Rocks”, freshly cleaned and sparkling, with the Louvre’s earlier version, will not be repeated.

'Portrait of a Young Man, The Musician' (c1486-87)

The story begins with Milan’s 1485 “Portrait of a Musician”, depicting a young man – Leonardo’s only known painting of a male sitter – in an animated three-quarters pose who seems, from the hint of mobility about his lips and song sheet in his hand, to have just finished singing. Like most of Leonardo’s paintings, the authenticity of this one has been long disputed but curator Luke Syson is surely right that many features – the cascade of curls with their rippling highlights, resembling those of the angel in “The Virgin of the Rocks”; the moist, properly spherical eyes; the precise, obsessive regard for the fall of light; the whiff of melancholy; most of all the suggestion of movement – mean that it could be by no one else. Inclining to engage the viewer, the youth is frozen in time as a sentient, emotional being – by an art, this painting boasts, that outlasts music.

If this work revolutionised static notions of portraiture, “Portrait of Cecilia Gallerani (The Lady with the Ermine)” capitalised on the sitter’s unique status as Sforza’s beloved 15-year-old mistress to make a radical likeness freed of constraints. Its ambivalence and erotic undercurrent would have been inadmissible in a bridal portrait, yet its gravitas and refinement – in the smooth translucent half-tones of the face, careful applications of lighter colours pulled over darker modelling, contrast of costly jet beads with pale skin – are entirely appropriate for a court commission.

'Drapery Study for the Right Sleeve of St Peter' (c1493-96)

With her head angled to the right and her body to the left, Cecilia turns to listen – a twist of movement as arresting as the liquidity and intelligence suggested by the catch-lights in her eyes, which look intriguingly beyond us, by the Mona Lisa-like half smile, and the sensuous stroking, by her too-large hand, of a frisky ermine, a Sforza symbol. As with the Mona Lisa, we cannot divine Cecilia’s thoughts, which seem to change – warm, distant, self-contained, receptive – every time we return to the picture. The work’s patterning – divided into horizontal lines by the necklace, black fillet across the forehead, gold border of the transparent veil – is formal. Renaissance viewers probably responded to the idea that the harmonious beauty reflected Cecilia’s moderate, calm character; contemporary ones are drawn to her elusiveness.

Evidently, a Madonna had to be more idealised: St Petersburg’s “Madonna Litta” is displayed here alongside a life drawing of a stunning model whose serene features are rationalised and perfected in the finished painting. This imaginative sense of an unknowable inner life with which Leonardo animated secular portraits brought about, too, a new sort of religious painting.

'Studies of Hands' (c1489-90)

“Suddenly two things arose in me,” reads his notebook, describing standing at the mouth of a cave, “fear of the menacing darkness and desire to see if there was any marvellous thing within.” In “The Virgin of the Rocks”, he recreates that moment. One has to imagine the candle-lit chapel of the Confraternity of the Immaculate Conception who commissioned (then wrangled over) the piece. That setting would have made yet more mysterious, in a work of tremendously subtle tonal unity and a reduced palette, the way there emerges from the shadows of painted rocks and a glittering carved frame, four figures – Mary cradling with one hand a praying infant, John the Baptist, while her other hand hovers protectively over the baby Jesus, attended by a diaphanous angel .

It is almost detective work – compelling, endless, ultimately unnecessary – to analyse differences between the more delicate, meticulous Louvre version, in poor condition, and the more sculptural, monumental London picture, whose natural setting is more generalised. Both utilise Leonardo’s famed layered glazes and sfumato, blurred outlines and mellowed colours; both compositions depend on the central drama of Mary’s twisting action, at once dynamic and frozen, and enhanced by the diagonals of her cloak and the strong crumpled folds of its golden lining, as she leans towards the innocent/wise holy children. The pyramid of four figures is perfectly proportioned, almost geometric, balancing the realistic setting of remote stony ground, sea – the source and end of all water as Mary is conduit for all grace – and crepuscular light. Everything, as Goethe wrote in 1787, is “both natural and rational”.

'St Jerome' (c1488-90)

A century later, Hippolyte Taine enthused how these figures “overflow with unexpressed ideas and sensations”. There is a Leonardo for every age; often, too, the artist seems to condense within his own language styles centuries ahead: here the Vatican’s unfinished “St Jerome”, the saint’s emaciated ascetic body paralleled by the barren rocks surrounding him, heralds the psychological intensity of the baroque, while a newly attributed “Christ as Salvator Mundi” has the weirdness of symbolism and surrealism combined. Works by Leonardo’s circle, dutifully included for historical context, by contrast look locked in time. Although one hardly glances at them, they do not distract from an infinitely rich show, fleshed out by drawings that would themselves, in less glamorous and privileged circumstances, constitute a fine exhibition.

‘Leonardo da Vinci: Painter at the Court of Milan’, National Gallery, London, to February 5. www.nationalgallery.org.uk

Watch Jackie Wullschlager’s video tour of the exhibition at ft.com/arts-extra

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