There is one gesture that, more than any other, sums up Leonardo da Vinci: the tip of a pen or chalk sliding across the page, following the movement of things. Even before he was a painter, engineer, or anatomist, Leonardo was someone who drew in order to understand. The Codex Atlanticus, now preserved in the Veneranda Biblioteca Ambrosiana in Milan, is the most extensive—and perhaps the most surprising—testimony to this way of thinking with the hand.
Behind that name, which evokes distant geographies, there is no esoteric mystery: ‘Atlantic’ was simply the format of the large volume that collected the sheets, as big as a geographical atlas. But within those pages, a world unfolds: over a thousand sheets covering Leonardo’s entire biographical and intellectual career, from his early years in Tuscany to his death in 1519.
LEONARDO DA VINCI. Il Codice Atlantico
6 dicembre 2025 – 7 giugno 2026
Chiostro maiolicato di Santa Chiara, Napoli
From Leonardo’s legacy to Pompeo Leoni’s “collage”
When Leonardo died in France in 1519, he left his writings and drawings to his favorite pupil, Francesco Melzi, who jealously guarded them in the family villa in Vaprio d’Adda. Melzi was well aware that he had a unique heritage in his hands and protected it until his death around 1570.
His son Orazio, however, did not share this awareness. It was during this generational transition that the writings were scattered, sold, transferred, and dismantled. At the end of the 16th century, Pompeo Leoni, a Milanese sculptor, entered the scene and managed to obtain a large quantity of Leonardo’s papers and notebooks.
With a criterion that today we would define as more “expository” than philological, Leoni took scissors and glue, cut, trimmed, and reassembled the sheets on large supports, bringing together materials that were very different in terms of period and content but visually effective. This gave rise to two fundamental collections:
- the volume of anatomical and naturalistic drawings, now in Windsor;
- the large corpus of studies, projects, and notes that would later be named the Codex Atlanticus.
In 1637, Count Galeazzo Arconati donated this extraordinary collection of sheets to the Biblioteca Ambrosiana, together with eleven other notebooks by Leonardo, to ensure their preservation and transmission to posterity. It was a gesture that reflected the mission of the library established by Cardinal Federico Borromeo: to promote culture, facilitate study, and cultivate beauty for the benefit of the community.
Napoleon, Paris, and a “near” missed return
The history of the Codex Atlanticus is also intertwined with that of Europe. In 1796, Napoleon Bonaparte entered Milan and ordered the confiscation of the most important works in the occupied territories. The Codex and the eleven notebooks were transferred to Paris.
It was on that occasion that, in the French lists of stolen works, the volume was described as “Atlantic in format”: hence the name by which we still know it today. The Codex remained in France for about seventeen years, until the Congress of Vienna (1814–1815), when the European powers forced France to return what it had stolen.
The return of the Codex Atlanticus to Italy happened almost by chance—or through enlightened obstinacy. The Austrian commissioner in charge of identifying the Ambrosian works, an elderly man with little knowledge of art and science, was about to leave it in Paris, mistaking Leonardo’s mirror writing for Chinese characters. It was Antonio Canova, on a mission to recover the works stolen from the Vatican, who intervened decisively and demanded their return.
The Codex thus returned to Milan. The notebooks, however, would never return.
For a long time, however, the manuscript remained an object that was more venerated than actually studied: enclosed in a precious case designed by goldsmith Alfredo Ravasco and placed in the Leonardo Room, it could be admired but not consulted. It was only in the second half of the 20th century that the realization dawned that, in order to truly understand Leonardo, his papers needed to be restored to mobility, legibility, and accessibility.
From volume to sheets: a new life for the Codex
In 1968, the Codex left the Ambrosiana for the abbey of Grottaferrata: the monks, armed with patience, detached the sheets one by one from the heavy 16th-century papers on which Pompeo Leoni had mounted them, transferring them to new supports. This resulted in the 1,119 sheets we know today, bound in twelve volumes and kept, since the 1990s, in the Ambrosiana’s Treasure Room: a vault with constant temperature and humidity, designed to ensure maximum conservation security.
In 2008, there was a further turning point. An international commission of scholars and curators decided to unbind the volumes and place each sheet in an acid-free passe-partout, without touching either the originals or the 20th-century supports. It was a paradigm shift: no longer the Codex as a single, imposing closed volume, but as a collection of sheets that could be studied, exhibited, and rotated.
To make this new arrangement possible, the vault was also redesigned: the twelve bindings were replaced by 120 storage boxes. Since then, some of the Codex’s sheets have been exhibited on a rotating basis in the Sala Federiciana, the large Ambrosian reading room. The conservation rules are strict: each sheet can only remain in the light for 90 days, then it must ‘rest’ in the dark for three years. It is a delicate balance between protection and enjoyment, which makes targeted exhibitions possible—such as the one in the monastery of Santa Chiara—while at the same time protecting the fragile material of genius.
Drawing is not representing: it is knowing
But what makes the Codex Atlanticus more than just a collection of extraordinary sheets? The answer lies in the way Leonardo thinks.
The pages of the Codex contain studies of mechanics and hydraulics, designs for war machines, hydraulic devices, architecture, mathematical and astronomical problems, sketches for paintings, fables, and philosophical reflections. The variety of topics is dizzying, but there is a single thread that ties them together: drawing as a tool for understanding reality.
For Leonardo, drawing is not about imitating forms, but dismantling and reassembling them, following their movement, and grasping their laws. Reality is not a repertoire of images to be copied, but a complex organism that reveals itself only to those who question it patiently, returning repeatedly to the same phenomena, correcting, clarifying, and comparing.
Aerial perspective—the way of pictorially rendering bodies immersed in the atmosphere, filtered by light and distance—arises precisely from this attitude. Leonardo observes how contours become more blurred with increasing distance, how colors shift toward blue or gray due to the effect of the intervening air, how contrasts gradually soften. He studied the anatomy of the eye, formulated hypotheses on how images are perceived, and explored meteorology, the physics of light, and perception.
Perspective is no longer a rule of geometric construction, but a consequence of the physical conditions of the environment: painting and science, in his view, are two sides of the same investigation.
The same thing happens when Leonardo studies the human body. His dissections, conducted with a rigor that still amazes modern doctors, certainly help him understand how we are made: bones, muscles, internal organs, heart, lungs. But there is another question that obsesses him: how does an emotion translate into a gesture, a facial expression, a posture?
Physiognomy, that is, the attempt to read character from features, was still linked to the thinking of his time. Leonardo, however, transformed it into a laboratory: he related anatomical structure, behavior, and the manifestation of passions. The famous grotesque heads preserved at the Ambrosiana—caricatured, deformed, exaggerated faces—are experiments on how the face can become the language of emotions, on how the graphic sign can “write” anger, stupidity, fury, greed.
For him, movement is twofold: the physiological effect of a muscular structure and, at the same time, an expressive signal. To represent a gesture truthfully, the artist must understand the mechanical laws that generate it and the emotional dynamics that motivate it.
Once again, drawing is the point where these two levels meet.
Jaspers and the limits of genius: why Leonardo did not found modern science
The philosopher Karl Jaspers made a crucial point: Leonardo is not the ‘founder’ of modern science, nor could he be. In him, scientist, artist, and technician coincide; his knowledge is not organized into a single discipline, but into a universal knowledge that brings together different fields without ever clearly separating the gesture of the artist from that of the scientific observer.
This unity is his greatness, but also his limitation: modern science will arise from specialization, from the formalization of laws, from a shared mathematical language that was not yet available in Leonardo’s time in the way it would be a century later. Yet, in many pages of the Codex Atlanticus, a method that heralds the scientific method is already visible: direct observation, systematic comparison, verification, correction, awareness of limits.
The dream of flight: from imitation to analysis of limits
Few areas illustrate this transition better than the studies on flight. The idea that man could rise into the air like a bird fascinated Leonardo from a young age. He drew wings, studied the structure of feathers, analyzed the movements of takeoff and landing, and imagined winged machines powered by the strength of the arms.
The pages of the Codex on the Flight of Birds, now in Turin, document his meticulous work: diagrams, sketches, calculations, and notes. At a certain point, however, his analysis led him to a bitter but lucid conclusion: human flight, based on the direct imitation of flapping wings, is not possible. The muscle power required to move a wing large enough to support the body exceeds human capabilities.
Here, the drawing changes function: it is no longer just a project, but a record of a defeat that becomes knowledge. Leonardo understands that flight cannot come from the mechanical copying of birds, but from a different way of using air, weight, and lift. Lightweight materials, engines, and a complete physical framework are still lacking; his intuition therefore remains confined to the theoretical realm. But the transition from dream to awareness of limits is entirely modern.
Christ, Judas, and the unfinished: when the mark stops
The same awareness also emerges in the most delicate area: religion. According to a well-known but controversial and fascinating suggestion by Gian Paolo Lomazzo, Leonardo deliberately left the faces of Christ and Judas unfinished in The Last Supper.
If drawing is for him a definition of reality, the closure of a form that has been understood, what does it mean not to finish a face? In the Christian tradition, Christ is the highest good, Judas the traitor par excellence: absolute good and evil, poles that escape our conceptual grasp.
Taking his logic to its extreme consequences, Leonardo seems to intuit that what is radically beyond human measure cannot be fixed in a single image. The unfinished, in this case, is not a distraction or an accident, but a gesture of respect: the mark stops where intelligence recognizes that it cannot fully comprehend.
Just as he recognizes the limits of the “human machine” in flight, he identifies the limits of visual language in the face of the absolute in the faces of Christ and Judas. Incompleteness then becomes a further sign: the sign of a knowledge that is aware of its own boundaries.
The eye, the hand, the world
At the center of everything, for Leonardo, is the eye: “first minister of nature,” window of the soul, instrument through which the mind receives the proportions and forms of things. The hand obeys, translating into signs what the eye has seen and the intellect has ordered.
In the Codex Atlanticus, this triangulation is constant: eye, mind, hand. Each sheet is a fragment of this dialogue, a stage in a thought process that is never satisfied with a single answer. For Leonardo, drawing means ordering the world, but also accepting that part of it remains irreducible to the sign.
This is perhaps why, when looking at his sheets, the feeling is not only one of admiration but also of participation: those meticulous and often dense lines show not only what Leonardo saw but also how he learned—and invites us—to see.
Drawing to understand, in fact: a lesson that, five centuries later, continues to challenge us.
