The Last Leonardo: The Making of a Masterpiece. Ben Lewis

The painting had vanished from sight for a total of 184 of its estimated five hundred years of existence – 137 years between 1763 and 1900, and another forty-seven years between 1958 and 2005. When the great British art historian Ellis Waterhouse saw it at an auction in London in 1958, he scribbled one word in his catalogue: ‘wreck’.

      Robert Simon was on a high-risk mission. He hadn’t even been able to afford the insurance premium for the full worth of his hand luggage. The auction house Sotheby’s had helped him in the end by kindly writing a low valuation of the painting at only $50 million. His piece was fragile. He wasn’t sure it would survive the plane trip, let alone make it onto the walls of a world-class museum or into the saleroom of a famous auction house. The panel on which the painting had been executed had been pieced back together and beautifully restored, but under its freshly varnished surface lay a hidden flaw: a huge knot in the lower centre. When it was studied by technical panel specialists in Florence, they said it was the worst piece of wood they had ever seen.

CHAPTER 2

       The Walnut Knot

      The countryside north of Milan sweeps slowly up towards the still blue lakes and then the jagged outline of the Alps. Before the land rises to alpine heights there are foothills and farmland that were once dotted with walnut trees, whose thick canopies of smooth-edged leaves shuffled in breezes and shook in winds. Their dense webs of branches broke up the hot sunlight, and farmyard cats scratched their backs on the trees’ distinctive, deeply furrowed dark bark. The trees grew quickly, developing thick trunks – up to two metres in diameter – and lived up to two hundred years. They are mentioned in medieval Italian legends about female shamans who summoned the spirit world by dancing around them. Millennia earlier, according to Roman myth, Jupiter, the most powerful of all the gods, subsisted on walnuts when he walked among men.

In his notebooks, Leonardo studied the structure of the walnut and other trees in the same way he studied so many other phenomena of the natural world. He observed how the colouring of the leaves was a product of four things: direct light, lustre (reflected light), shadow and transparency. He went on to analyse more complicated principles governing the structure of trees. He discovered one of the basic mathematical laws of their growth, that the combined size of a tree’s branches is equal to the width of its trunk, and the smaller branches that spring from larger ones follow the same proportional rule. At the heart of Leonardo’s life work was this pairing of the minutely detailed observation of nature with an understanding of the principles governing the appearance and behaviour of things, which today we call empiricism. For Leonardo, something had to be understood before it could be drawn. In a note dated April 1490 in his largest set of notes, the Codex Atlanticus, he wrote: ‘The painter who merely copies by practice and judgement of the eye, without reason, is like the mirror, which imitates within itself all the things placed before it without cognition of their existence.’ In Leonardo’s paintings, the detail can be overwhelming. Each leaf, each fold of cloth, each curl of hair can be different from the one beside it, yet each may share the same formal structure.

Leonardo’s mind was poised between the medieval and the modern eras,* which is one of the reasons he is such an iconic and mysterious character today. His notebooks give the thrilling sensation that the modern idea of knowledge is being invented on their pages. The Codex Atlanticus contains, amid the drawings of machines, aeroplanes, weaponry and human anatomy on its 1,119 pages, enigmatic prophecies that double as riddles for court entertainment, a literary genre dating back to the Middle Ages.1 For example: ‘There shall appear huge figures in human shape, and the nearer to you they approach, the more will their immense size diminish’ (shadows), and ‘You shall behold the bones of the dead, which by their rapid movement direct the fortunes of their mover’ (dice). He also predicted that ‘There will be many who will be moving one against the other, holding in their hands the sharp cutting iron. These will not do each other any hurt other than that caused by fatigue, for as one leans forward, the other draws back an equal space; but woe to him who intervenes between them, for in the end he will be left cut in pieces’ (a saw). The humble walnut tree, too, receives a mention here: ‘Within walnut trees, and other trees and plants, there shall be found very great hidden treasures.’ The walnut tree from which the single plank of wood was hewn on which the Salvator Mundi was painted was not concealing treasure, but it – or at least the section used for our painting – did hold its own secret: a deformity dangerous for artists.

      For many years the tree from which the Salvator Mundi sprang would have performed its duty providing nuts for culinary and medicinal purposes. Its annual harvest would have enriched Renaissance pasta dishes such as spiced walnut linguine, or fig and walnut ravioli, or would have been combined with the tops of the bitter rue plant in concoctions to ward off the plague. Then one day the decision would have been made to sell the wood of the tree. It would have been dug up with spades rather than felled with an axe, since the best wood is near the base. Some of the timber would have been used to make ornate carved tables, chairs and caskets for the homes of noblemen. Other blocks would be reverentially carved into statuettes of saints and placed on the ends of choir stalls, or in the niches of altars. The finest parts would be used for the intricate Renaissance craft of intarsia, or wood inlay: different types of wood, each a different shade, were cut into delicately shaped strips to build sepia pictures of landscapes or religious scenes, which were set into cabinets and desks. This walnut tree was cut into planks for all these purposes, and a single plank, 45cm wide and 66cm high, would become our painting.

The walnut timber of the Salvator Mundi was brought on a cart to Milan, a city with a population of between 150,000 and 300,000 people. Three times the size of Florence, Milan was evolving in concentric rings, its population spilling out beyond the city walls into new suburbs. The nobles lived in high-walled palaces, with thick rusticated façades, behind which lay inner courtyards with trees and fountains and sculptures on pedestals, cut off from the noise of the street. The city skyline was dominated by the Duomo, the cathedral, in the centre, and in the north-west by the Castello Sforzesco, the palace of Milan’s ruler, Duke Ludovico Sforza. There were shipyards, taverns, bakeries, a debtors’ prison, cloth and shoe shops. There were quarters specialising in different trades: one full of mills producing cloth and paper, or sawmills for cutting wood; another grouping artisans working with wool; another with metalworkers. There were 237 churches, thirty-six monasteries, 126 schools and over a hundred practising artists. Milan was, in Leonardo’s own sharp words, a ‘great congregation of people’ who were ‘packed like goats one behind the other, filling every place with fetid smells and sowing seeds of pestilence and death’. There were periodic outbreaks of bubonic plague, which would one day kill several of Leonardo’s assistants. Leonardo, who was (at least in his own mind) an urban planner as well as an artist and scientist, concocted plans to redesign the city, but they never left the drawing board.

      Somewhere in the narrow streets of Milan was the carpenter or panel-maker who supplied the wood for the Salvator Mundi. This kind of artisan was the first of several craftsmen involved in the execution of a Renaissance work of art such as the Salvator. They were often required to construct large and intricate surfaces for paintings, building up a flat surface from planks of wood connected with animal glues and grooved joints, and combining panels of different shapes into elaborate altarpieces with wings on hinges. But the creation of the walnut panel for the Salvator Mundi was a relatively mundane task, since it was cut as a single piece of wood; it is therefore all the more strange that it was so poorly executed.

Leonardo may well have ordered a batch of panels, since two other Milanese paintings of his on walnut wood have been scientifically analysed and shown to have come from the same tree. The size was standard for devotional paintings, for which there was a large demand among wealthy Italian families. Typical subjects were the Virgin and Child, various saints including John the Baptist, and Christ, carrying the cross, crowned with thorns or as the Saviour of the World. Such pictures were hung in the owner’s bedroom or private chapel.

      Wood has to be prepared for painting with various undercoats, just as canvas is usually primed. In fifteenth- and sixteenth-century