Click here to skip to content

Leonardo da Vinci's notebooks - overview

The manuscripts

  • Leonardo's surviving manuscripts consist of some 7,000 pages of notes and drawings, bound and unbound: about half of what is believed to have existed at the time of his death; they are the most important sources for understanding Leonardo's work as a natural philosopher, engineer, and (in addition to his finished paintings), an artist.
  • They are written primarily in Italian, unusual for learned European writings of the time which were usually in Latin; they are in Leonardo's characteristic mirror script, written from right to left, so that they can be read when held in front of a mirror.
  • Leonardo's prolific manuscript legacy documents scientific and technological practice before the scientific revolution; comparatively few manuscripts by his contemporaries have survived.
  • Part of Codex Arundel, and the whole of Codex Leicester, were composed around 1508-1510; they were begun in Leonardo's native Tuscany and probably returned with him to Milan in late 1508.

Why is putting these two notebooks together significant?

Bringing these two notebooks is signficant for three reasons:

  • It is the first time they have been displayed together in their entirety since Leonardo composed them - possibly ever!
  • They are his two manuscripts that deal primarily with scientific topics, and show Leonardo in the persona of what we would today call a scientist.
  • They raise intriguing questions about the provenance and composition of the manuscripts.


  • Most of Leonardo's manuscripts were gathered together by Leonardo at the time of his death and kept by his pupil and heir Francesco Melzi, but were subsequently dispersed, traded and inherited by artists and collectors and their heirs.
  • Since the 16th century, Codex Leicester has been retained by a series of private collectors: for 263 years (1717-1980) belonging to the estate of the Earl of Leicester, Thomas Coke, and his heirs, after whom the Codex was then and (following a brief period known as 'Codex Hammer' when in the collection of industrialist Armand Hammer, 1980-1994) is now named.
  • Codex Arundel was in the collection of notable art collector Thomas Howard, the Second Earl of Arundel on his death in 1646 and donated by his grandson to the Royal Society (c.1667) then transferred to the British Museum library (now the British Library) in 1831 with other Arundel MSS. It has therefore been retained by scientific and public institutions for the best part of 300 years.

What do scholars hope to learn as a result?

  • Online comparison of the digitised manuscripts will make it easier for scholars to identify and compare passages in the two codices.
  • This in turn provides clues to the composition and original order of the manuscripts.
  • The two codices provide an overview of Leonardo's scientific thought around 1508-1510, and, in the case of Codex Arundel, of the evolution of his thought over time (c.1478-1518).
  • There would be great benefit in digitising and bringing all of Leonardo's manuscripts together online.

What benefits to researchers and archives does the digitisation of the notebooks offer?

  • The digitising of the codices offers unprecedented access to the manuscripts, which have hitherto been available for specialised research in leading international libraries and private collections, and occasionally exhibited.
  • Digitisation offers the possibility of the reconstruction in the order he composed them, and the reordering of the manuscripts for the purpose of study (for example by subject or place).
  • Digitisation of the codices offers benefits for the preservation of the original manuscripts by reducing the need for handling the original manuscripts.
  • Now that both original codices are unbound, digitisation allows us to create an image of the bound order in which the manuscripts were preserved from the 16th to 20th centuries, thus providing an important historical record of how the manuscripts were kept for much of the past 500 years.

What insight into the mind of Leonardo can we gain as a result?

  • Leonardo worked on loose sheets of paper (usually consisting of 4 pages, 2 on each side) and generally kept his thoughts on each topic confined to one sheet.
  • Passages he copies elsewhere in his notebooks are crossed out, suggesting a relationship between the ordering of his thoughts and the ordering of his papers.
  • His intention to order and publish his manuscripts was never fulfilled, as his ideas proliferated and developed over time.
  • The manuscripts show a wide-ranging curiosity and Leonardo's sustained application to scientific and technical problems (as well as artistic and moral ones) on most conceivable subjects.
  • Leonardo returned to many of the same ideas and problems repeatedly throughout his work.


  • About one third of the Codex Leicester relates to water and its movement, and there are several passages relating to water in the Codex Arundel (f. 149r), associated with canalisation projects in Tuscany and France (f. 269r). Leonardo's observations led him to elucidate how currents flow: 'By so much as you will increase the river in breadth, by so much will you diminish the speed of its course.'
  • In some cases linked to his studies of water was Leonardo's discussion of the changing character of the earth including phenomena such as erosion (Codex Leicester, 5v, 32r, 31v) the global circulation of water (Codex Arundel 210r, 236v) and wind (Codex Leicester 30v, Codex Arundel 113v).
  • Among the most famous studies in the Codex Leicester are those exploring the geometry and astronomy of the sun, the moon and the earth (ff. 1-2, 35 and 36) paralelling those in the Codex Arundel (e.g. f. 104r). This was a key topic in medieval cosmology, and Leonardo, while retaining the Ptolemaic system, developed a geometrical argument for the reflection of light from water on the surface of the moon to illuminate the earth. This implied that the moon, like the earth is possessed of gravity, keeping the four Aristotelean elements, earth, water, air, and fire, in place in order of density.
  • As Leonardo studied the geometry of light on a cosmological scale, he also considers optical questions of human proportions. In the Codex Arundel (e.g. ff. 87v-88r), Leonardo considers Alzahen's problem (after the Islamic philosopher of the 10th century, Ibn al-Haitham Alzahen) concerning where an object at a given location is seen in a curved mirror. He also suggests an experiment to coat a mirror with tempera paint removed in thin lines to see the separated rays reflected. Leonardo was interested in the utility of concave mirrors for concentrating light rays on a single point to create heat and fire, recalling Archimedes who used a burning mirror to destroy enemy ships to defend Syracuse. After 1513 in the service of Giuliano de Medici, commander of the papal forces, Leonardo experimented with burning mirrors. Elsewhere he considers the optical properties of the eye (Codex Arundel f. 115v).

Is there anything in the notebooks that can be linked to modern scientific ideas or developments?

Leonardo initially held the traditional view of the continuous circulation of water on the earth. In La composizione del mondo (1282), Ristoro d'Arezzo, following Pliny the Elder who argued that the highest seas were higher than the highest mountains (f. 3r), envisaged a siphonic process in which water from the sea was drawn to the highest mountains, released in springs and flowed downstream to form rivers thence back into the sea. However, in the course of composing the Codex Leicester, Leonardo changed his thoughts on this subject to conclude that precipitation, the evaporation of water to form clouds and rain explained the gathering of water above the earth, and that the force of water in turn formed the mountains and valleys through erosion.

The debate in Leonardo's manuscripts about the global circulation of water was key to another point upon which Leonardo distinguished himself from medieval scholars who supported the notion of the Biblical deluge as the origin of fossils found atop mountains.

Leonardo found fossils to be buried in ordered layers and explained the process of sedimentation that led to their formation (Codex Leicester, f. 8v), designing experiments in glass tanks to demonstrate this process (f. 9v). Yet conventional wisdom on the origin of fossils and the history of the earth was dominant until the work of Charles Lyell (Principles of Geology) in the 19th century.

While Leonardo's idea that the moon is covered with water was wrong, he correctly explained the secondary light of the new moon, lumen cinereum as light reflected from the seas of the earth. (Codex Leicester, f. 7r)

In the Codex Arundel (ff. 67r-66v), Leonardo shows with clarity how the principles of a balance work as codified by Jordanus de Nemore in the 13th century. Equilibrium can be found when the result of multiplying the length of the arms by the weight is the same on both sides. Leonardo further stressed that the weight of the arms also needs to be taken into account. He applied this principle to the case of uneven balances with one short arm and one long arm, useful in weighing heavy objects and thus suitable for engineering projects (f. 66r).

Elswhere in the Codex Arundel (ff. 40v, 41r), Leonardo also identified friction as proportional to the force and therefore weight of the objects in contact, a principle formulated by Guillame Amontons in 1699.

Another example of Leonardo's grasp of mechanics is his discussion of stationary waves on f. 23r of the Codex Leicester, in which he explains 'waves do not penetrate one another, but leap back from the percussed place, and every reflex motion flies away at equal angles from the percussion place'. Christian Huygens reformulated the same principle in 1673, when it became more widely known and established.

Leonardo was not only an inspired engineer, he also delved more deeply into the philosophical basis of things. Although Albert Einstein condemned what Leonardo wrote on the concept of nothingness (Codex Arundel f. 131v) as 'absolute nonsense', Einstein conceded that Leonardo nonetheless conceived of space and time as 'reciprocally independent.continuous entities of point-like nature (deprived of extension) in constant contact' and perceived the non-extended character of time present as a problem.

Some more of Leonardo's more interesting insights and designs

  • Leonardo discusses the problem of submarine warfare (Codex Leicester, f. 22) and draws a design for an underwater breathing device (Codex Arundel, f. 25v)
  • In the later part of his life, while in the service of the King of France (Francis I), Leonardo worked on plans for a new château at Romorantin (f. 264r, 270v).
  • Leonardo addressed the problem of perpetual motion (e.g. Codex Arundel, f. 44v), eventually concluding that this was not possible.
  • Two pages of about 1506-1508 in the Codex Arundel (ff. 224r and 231v) pertain to a mobile stage set that Leonardo was designing for the staging of Poliziano's Orpheus.

Are there any modern scientists or inventors particularly inspired by Leonardo?

Leonardo's design for a bridge over the Bosphorus proposed in a letter to the Turkish Sultan preserved in another manuscript (not shown on TTP) was built by the artist Vebjorn Sand at Aas (20 miles south of Oslo, Norway).