Leonardo da Vinci’s scattered manuscripts and notebooks reunited after 400 years

The Codex Atlanticus and the Windsor folios can once again be viewed together: a digital reconstruction brings order to Leonardo’s chaos.

On a single page of Leonardo da Vinci's manuscripts, a horse, a gear, a note on water, a canal-digging machine, and a barely sketched human profile could all coexist. The problem has always been this: Leonardo thought in terms of connections, whereas for centuries, a vast portion of his folios was interpreted through practical divisions—orderly but hardly in the spirit of Leonardo. Art on one side, science on the other. Figurative drawings in one place, technical notes in another. As if the same hand, in the course of a single afternoon, could truly switch brains depending on the subject.

The new Leonardotheka 2.0, accessible online starting June 8, 2026, attempts to bridge this divide—at least digitally. The platform links the folios of the Codex Atlanticus, held at the Ambrosian Library in Milan, with those in the Royal Collection at Windsor. It thus makes a consultation of a monumental collection of pages, images, transcriptions, and study notes available. The numbers illustrate the scale of the project: more than 1,000 folios of the Codex Atlanticus and approximately 550 held at Windsor, for a total of thousands of handwritten pages that can now be explored through cross-referenced searches.

The historical division

The separation dates back to the late 16th century, when Pompeo Leoni, a sculptor and collector, began working on the documents he inherited after Leonardo’s death. He cut, dismantled, and reassembled them. He placed the most technical and scientific studies in a large album, which later became the Codex Atlanticus, and gathered numerous figurative, anatomical, naturalistic, and landscape drawings elsewhere. Viewed from a distance, this process follows a certain archival logic. Viewed up close, however, it ultimately confined Leonardo to categories that were too narrow for him.

After the master’s death in 1519, the manuscripts passed into the hands of his student Francesco Melzi. From that point on, they were moved from place to place, changed hands, and were scattered. The Codex Atlanticus then came into the possession of Count Galeazzo Arconati, who donated it to the Ambrosian Library in 1637. The other core collection, comprising of numerous figurative folios, made its way to England in the 17th century and entered the Royal Collection around 1670. Since then, Milan and Windsor have held two distinct parts of the same body of work.

This division also influences how Leonardo’s work is interpreted. The painter of faces and bodies. The engineer of machines. The specialist in anatomy. The observer of water, flight, animals, and light. All of this is true, of course. But when taken in pieces, it becomes easier to market and harder to understand. In his sketchbooks, a drawing often reveals itself to be a technical concept already; the scientific note passes through the artist’s eye, and the image serves to reason even before it reveals.

A partial reconciliation

Leonardotheka does not physically bring these documents together. The sketches remain in Milan and Windsor, protected by separate institutions and subject to specific conservation requirements. The reconstruction takes place on screen, with all the limitations of the digital format: it does not reproduce the paper, the thickness, the smell, or the actual scale of the folio as seen in person. However, it offers an essential opportunity for researchers: the ability to compare separate documents, follow leads, verify correspondences, and connect pages that once belonged to the same collection.

Within the platform, users can search for topics, techniques, media, transcriptions, bibliographic references, or even links between folios. The most tangible aspect involves the digital reconstructions of original pages that have been dismantled over the centuries. Researchers have identified at least fifty confirmed reconstructions by matching fragments preserved at Windsor with folios from the Codex Atlanticus. To do so, they followed material clues: paper dimensions, watermarks, sheet preparation, writing instruments, graphic marks, and physical compatibility.

Among the most interesting examples is the reuniting of a drawing of a horse with a written reflection on the Regisole, the ancient equestrian statue that once stood in Pavia. According to the researchers, this connection could help interpret Leonardo’s work on the grand monument to Francesco Sforza—that immense, unfinished horse that remains one of his most famous undertakings precisely because it was left unfinished. Here, digital technology serves less to dazzle than to accomplish an almost modest task: placing two pieces side by side and seeing what happens.

Leonardo without a showcase

Faced with such archives, the temptation is to turn everything into an event. Leonardo is a surefire draw: the name alone is enough, and every project risks becoming an automatic celebration. This time, however, the main interest lies elsewhere—in the opportunity to observe his work by breaking down the barriers between disciplines. The pages reveal a mind that proceeds by trial and error, accumulation, and backtracking. A machine next to an animal. A human body next to a mechanical problem. A magnificent drawing next to a pragmatic note. Not a static museum glorifying genius. Rather, a workbench, still cluttered.

This matters just as much to those who do not study Leonardo, for whom Leonardo is not their field of expertise. The myth of the absolute genius tends to distance him from us, turning him into a statue. The manuscripts have the opposite effect: they reveal the effort, the trials, the sketches, the cross-outs, and an almost feverish curiosity. In Leonardo’s pages, there's not only the finished work, but also the process. And sometimes, the journey is more interesting than the final result.

The platform also highlights a broader issue: the stewardship of cultural heritage in the digital age. Museums, libraries, and public institutions are entering a delicate phase, particularly with the rise of artificial intelligence and e-commerce giants. Digitizing an archive amounts to dictating how it will be searched, read, organized, and interpreted. This is not a neutral transition. In the case of Leonardotheka, at least, responsibility remains in the hands of scientific and cultural institutions, through a system designed for research and not merely for visibility.

The reunification of the documents therefore remains incomplete. No platform can erase four centuries of fragmentation, displacement, and dispersion. It does, however, allow these pages to return to a single visual field. A horse finds a sentence. A mechanism draws closer to an intuition. A fragment ceases, for a moment, to be merely a fragment. Leonardo, at last, becomes a little less orderly. And that is much better.

Source: Musée Galilée