The key to the Madrid Codex, "Leonardo da Vinci's mental laboratory"

Today housed in the National Library, the so-called Madrid Codices are considered one of the most important intellectual legacies of the Renaissance. They were two of the workbooks in which Leonardo da Vinci , with his characteristic mirror-image writing, recorded everything: his research, project notes, reflections, and so on.

It is in these manuscripts "where the most intimate and visionary part of his work emerges," molecular biologist and sculptor Andrea da Montefeltro explains to ABC. Together with Renaissance expert Annalisa Di Maria and art historian Lucica Bianch, he has spent years studying the genius's figure with a multidisciplinary approach, aiming to bring to light lesser-known aspects of his thought.

Although other fragments are known to exist in the Royal Collection at Windsor, the Biblioteca Ambrosiana in Milan, the Institut de France, the Victoria and Albert Museum in London, and the Royal Library in Turin, it is not known for certain how many notebooks he left behind upon his death. What is known is that he bequeathed his written work to Francesco Melzi , and that his son and heir, Orazio, divided the collection, with some of these notebooks ending up in the hands of the Mazenta brothers around 1585.

The sculptor Pompeo Leoni , associated with the court of Philip II, acquired many of them and brought them to Madrid, although after his death in 1608, all trace of them was lost. It was in the 1960s that two of them, known as the Madrid Codices, reappeared under unclear circumstances.

For researchers, their value lies not only in their individual contents, but in the collective work of the master's manuscripts. "The different codices are often read separately, when in reality they interact with each other : a drawing in one manuscript can find explanation or development in another. That's why the Madrid Codex is not an isolated document, but an integral part of a unified system that truly allows us to enter Leonardo's mental laboratory ," da Montefeltro emphasizes.

The molecular biologist maintains that with Da Vinci, surprise is always just around the corner. "Nothing in his writings is left to chance, not even the briefest notes ," he emphasizes. This has happened again with the Madrid II Codex. In one of his notes, Leonardo writes: "They will be better preserved if they are stripped of the bark and burned on the surface than in any other way." A seemingly secondary indication that, according to researchers, reveals an innovative procedure : the surface carbonization of wood as a preservation method.

In the Renaissance, wood was essential, the basis for bridges, ships, machines, and musical instruments. Leonardo himself reflected his interest in all aspects of this resource in the Madrid Codex. However, until then, wood preservation methods were mostly passive (Venetian stilt houses, for example, relied on immersion in water to take advantage of the anaerobic environment that slowed decomposition). In his manuscript, he proposed an active intervention : altering the properties of wood through direct manipulation—carbonization, which is now known to waterproof the material, make it more resistant to fire, and protect it from insects and fungi.

Montefeltro's team links this discovery to shou sugi ban or yakisugi , a Japanese wood burning technique documented only from the 18th century onwards. The researchers rule out the possibility that Leonardo could have known it because between the 15th and 16th centuries, Japan was practically isolated and yakisugi had not yet been documented.

On the contrary, they interpret the coincidence as a case of convergent invention: two distant cultures that, without contact, find the same solution to a common problem. However, researchers do not rule out the possibility that the exchanges that began in the 16th century between Spain, Portugal, and the East could have indirectly transmitted some of these ideas.

Beyond this hypothesis, the team emphasizes that each line in the codices can open up unexpected paths. "What emerges from this discovery is, above all, the awareness that in Leonardo's manuscripts, every detail can conceal valuable information ," Montefeltro summarizes. His team will continue to study these codices, not as isolated pieces, but as a comprehensive system of ideas in which art, science, and philosophy interact without borders.