Leonardo da Vinci: Painter at the Court of Milan

'The painter is master of all things that may come to a man's mind, and so if he wishes to see beauties of which he may become enamoured he has the power to make them… he is the lord and creator of them.'

A chill down the spine accompanies any confrontation with the undoubted talents of Leonardo da Vinci (1452-1519), whether in his inscrutable painted ladies or the first exhibit here: a tiny drawing of layers of scalp being peeled back like an onion, beneath which the brain is connected to the eye with an umbilical-like cord that links seeing and thinking, or observing and understanding. Yet, even when coming this close to the mental whirrings of a man so smart before his time and yet somehow so out of his own time, he remains a mystery.

This unprecedented gathering of what few paintings survive from Leonardo's hand (nine of fifteen, although no 'Mona Lisa', of course) gets us closer to his understanding of beauty, but it also tells a wider story about the end of medieval values in art and society. First a young 'Musician' (1486) is depicted, not in the traditional full side profile, but slightly twisted to the front, perhaps having just been animated by a piece of music. Leonardo, also prone to distraction and daydream, never finished this picture. It seems that once he had captured the desired effect, da Vinci moved on to the next whim. He might have suddenly decided to design a chariot armoured with scythes or draw a dodecahedron.

His next task might have been: how best to penetrate beneath the outward appearance of a woman? Rather than mere portraits of Milanese society, Leonardo caught his sitters lost in deep thought, staring into a middle distance - pensive, piercing. Symbols are everywhere: the jewels and brocaded dresses suggest a similar finery of character or spirit in his subjects, while Leonardo's dark painted backgrounds reinforce their three-dimensionality and interaction with the viewer. Or else, he just got bored at the edges and was itching to get away from the canvas, hence the unsatisfactory, skeletal 'Saint Jerome' (1488-90), forever about to beat his chest with a hastily sketched rock.

I might be boiled in oil or banished from the city walls for this opinion, but I infinitely prefer the Parisian version of 'The Virgin of the Rocks' (1481-85) to the later London painting. Yes, it needs a good clean, but not so much so that it would lose its characteristic 'sfumato' technique, a nutty smokiness that creates a haze of intrigue and softness in facial features that I associate with Leonardo at the height of his powers.

What is that pinnacle? The world's greatest artist, making this the greatest show on earth? I'm not sure, because while the masterpiece quotient is ridiculously high, there is much filler and work by underlings, put here chiefly to point out da Vinci's superiority. For all his omniscient Godliness and feverish intelligence, as Renaissance artists went, Leonardo accomplished relatively little in the field of painting (for his 'Last Supper', I raise you Michelangelo's Sistine Chapel ceiling). Leonardo, then, was a victim of his own imagination: no longer the boss of his brain, all those other competing supernatural powers put painterly pre-eminence just beyond him.