Ahead of His Time: Leonardo and The Codex Leicester

Codex Leicester, f.13v (1506–1510) by Leonardo da VinciOriginal Source: Codex Leicester

The Nature of Water

The Codex Leicester is a set of notes, written and illustrated by Leonardo da Vinci between 1506 and 1510, which reflect his observations and experiments on the nature and movement of water. 

While water is the Codex’s central theme, it also covers a variety of other scientific and technological subjects, including astronomy, geology, and hydraulic engineering.

The Codex has been owned since 1994 by Bill and Melinda Gates. Under their stewardship, the Codex has been the subject of numerous public exhibitions, print and digital publications, educational programming, and scholarly research.

A true scientist, Leonardo studied the world with intense curiosity and a keen analytical eye. 

In the pages of the Codex Leicester, through a combination of experiments both actual and imaginative, he asks questions and proposes answers – many of them accurate and ahead of their time.

Codex Leicester, f.036r (1506–1510) by Leonardo da VinciOriginal Source: Codex Leicester

Why is the sky blue?

On folio 36r, Leonardo devises an experiment with smoke and black velvet.

He used this experiment to demonstrate his correct hypothesis that the blue appearance of the air is caused by the darkness beyond it.

He used this experiment to demonstrate his correct hypothesis that the blue appearance of the air is caused by the darkness beyond it.

The Virgin of the Rocks by Leonardo da VinciThe National Gallery, London

The influence of Leonardo's understanding of the atmosphere is also evident in his paintings – for example, The Virgin of the Rocks in the National Gallery, London.

Codex Leicester, f.036r (1506–1510) by Leonardo da VinciOriginal Source: Codex Leicester

How Are Mountains Formed?

On the same page,
Leonardo theorizes that mountains and continents were once underwater...

... formed by underground caverns shifting and collapsing, the subsequent re-balancing of earth and water, and the re-centering of the earth’s center of gravity.

... formed by underground caverns shifting and collapsing, the subsequent re-balancing of earth and water, and the re-centering of the earth’s center of gravity.

Some aspects of Leonardo's theory about the formation of mountains are precursors to the modern scientific theory of plate tectonics.

Codex Leicester, f.002r (1506–1510) by Leonardo da VinciOriginal Source: Codex Leicester

What Causes the “Ashen Light” of the Moon?

On folio 2r, Leonardo hypothesizes that the glow of the dark part of the moon during the crescent phase is a reflection of light from the earth’s oceans.

This is the earliest known attempted explanation of the lumen cinereum, or “ashen light”, of the shaded portion of the moon. This phenomenon is now known as “earthshine”.

This is the earliest known attempted explanation of the lumen cinereum, or “ashen light”, of the shaded portion of the moon. This phenomenon is now known as “earthshine”.

Codex Leicester, f.003v (1506–1510) by Leonardo da VinciOriginal Source: Codex Leicester

What Causes the Circulation of Waters on the Earth?

Leonardo contemplates the then-prevailing theory that the heat of the sun draws water up from underground caverns to a mountain’s summit. 

On folio 3v, he rejects this theory based upon his observations of the natural world: mountain springs are not more active in the summer, when the sun is warmer.

He devises a distillation experiment which demonstrates that in an open system heat from above will pull air in instead of drawing water upward.

Codex Leicester, f.010v (1506–1510) by Leonardo da VinciOriginal Source: Codex Leicester

Why Are There Marine Fossils at High Altitudes?

Leonardo refutes the biblical account of the Deluge as the reason that seashells and marine fossils are found on high mountains.

On folio 10v, he hypothesizes that the Mediterranean Sea once covered much of Europe and North Africa.

He writes, “In Italy, where today birds fly in flocks, fishes used to move in great shoals”.

Codex Leicester, f.014v (1506–1510) by Leonardo da VinciOriginal Source: Codex Leicester

What Is the Action of a Drop of Water?

In folio 14v, Leonardo explores the dynamic effect of objects dropped in water:

spherical objects...

spherical objects...

and angular objects.

Leonardo’s closely observed drawing of a drop water foreshadows modern high-speed stroboscopic photography, which can capture images of objects moving too quickly for the eye to see.

Leonardo’s closely observed drawing foreshadows modern high-speed stroboscopic photography, which can capture images of objects moving too quickly for the eye to see.

Credits: Story

The Codex Leicester is in the collection of Bill and Melinda Gates. The British Library thanks the owners for permission to reproduce selected images from the Codex Leicester in this programme.

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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