The Nature of Water

Overview

Water was Leonardo's most sustained obsession. No other subject drew him back so consistently across so many decades — from his earliest Milan notebooks in the 1490s through his final years in France. The surviving writings on water constitute the largest single body of text in all of Leonardo's notebooks, totaling over 50,000 words.

Leonardo planned a comprehensive treatise on water, organizing his observations into what he called "fifteen books." The treatise was never completed, but the raw material survives: observations on waves, currents, erosion, floods, the movement of rivers, the behavior of water under pressure, the formation of whirlpools, and the analogy between water and blood in the body of the earth.

The Codex Leicester is dominated by water studies, but passages appear in nearly every surviving codex. Water was the thread that connected Leonardo's art (painting flowing hair, turbulent skies, river landscapes), his engineering (canal systems, hydraulic machines), and his natural philosophy (understanding the earth as a living system).

Leonardo repeatedly outlined the structure of his intended water treatise. These plans reveal his systematic ambition — and the gap between his organizational intentions and his chaotic working method:

Beginning of the Treatise on Water.

By the ancients man has been called the world in miniature; and certainly this name is well bestowed, because, inasmuch as man is composed of earth, water, air and fire, his body resembles that of the earth; and as man has in him bones the supports and framework of his flesh, the world has its rocks the supports of the earth; as man has in him a pool of blood in which the lungs rise and fall in breathing, so the body of the earth has its ocean tide which likewise rises and falls every six hours, as if the world breathed; as in that pool of blood veins have their origin, which ramify all over the human body, so likewise the ocean sea fills the body of the earth with infinite veins of water.

C.A. 171 r. b

Write first of all water, in each of its motions; then describe all its beds and the substances therein, always referring to the propositions concerning the said water; and let the order be good, for otherwise the work will be confused.

Describe all the forms taken by water from its greatest to its smallest wave, and their causes.

C.A. 74 v. a

The wave is the recoil of the stroke, and it will be greater or less in proportion as the stroke itself is greater or less. A wave is never found alone, but is mingled with as many other waves as there are uneven places in the object where the said wave is produced. At one and the same time there will be moving over the greatest wave of a sea innumerable other waves proceeding in different directions.

C.A. 84 v. a

If you throw a stone into a sea with various shores, all the waves which strike against these shores are thrown back toward where the stone has struck, and on meeting others advancing they never interrupt each other's course.

C.A. 84 v. a

Waves of equal volume, velocity and power, when they encounter each other in opposing motion, recoil at right angles, the one from the stroke of the other. That wave will be of greater elevation which is created by the greater stroke, and the same is true of the converse.

C.A. 84 v. a

Greater is the motion of the wave than that of the water of which it is composed.

C.A. 84 v. a

Whether the surface of the air is bounded by the fire, as is the water by the air and the earth by the water, and whether the surface of the air takes waves and eddies as does the surface of the water, and whether in proportion as the body of the air is thinner than that of the water the revolutions of its eddies are greater in number: of the eddies of the water some have their centres filled with air, others with water.

C.A. 42 r. a

I do not know whether it is the same with the eddies of the surface of the fire.

C.A. 42 r. a

Among straight rivers which occur in land of the same character, with the same abundance of water and with equal breadth, length, depth, and declivity of course, that will be the slower which is the more ancient.

This may be proved with straight rivers. That will be most winding which is the oldest, and that which winds will become slower as it acquires greater length.

Of waters which descend from equal altitudes to equal depths that will be the slower which moves by the longer way.

C.A. 156 r. a

The cause which moves the humours in all kinds of living bodies contrary to the natural law of their gravity, is really that which moves the water pent up within them through the veins of the earth and distributes it through narrow passages; and as the blood that is low rises up high and streams through the severed veins of the forehead, or as from the lower part of the vine the water rises up to where its branch has been lopped, so out of the lowest depths of the sea the water rises to the summits of the mountains, and finding there the veins burst open it falls through them and returns to the sea below. Thus within and without it goes, ever changing, now rising with fortuitous movement and now descending in natural liberty.

So united together it goes ranging about in continual revolution. Rushing now here now there, up and down, never resting at all in quiet either in its course or in its own nature, it has nothing of its own but seizes hold on everything, assuming as many different natures as the places are different through which it passes, acting just as the mirror does when it assumes within itself as many images as are the objects which pass before it.

C.A. 171 r. b

Among irremediable and destructive terrors the inundations caused by rivers in flood should certainly be set before every other dreadful and terrifying movement, nor is it, as some have thought, surpassed by destruction by fire. I find it to be the contrary, for fire consumes that which feeds it and is itself consumed with its food. The movement of water which is created by the slopes of the valleys does not end and die until it has reached the lowest level of the valley; but fire is caused by what feeds it, and the movement of water by its wish to descend.

C.A. 108 v. a

But in what terms am I to describe the abominable and awful evils against which no human resource avails? Which lay waste the high mountains with their swelling and exulting waves, cast down the strongest banks, tear up the deep-rooted trees, and with ravening waves laden with mud from crossing the ploughed fields carry with them the unendurable labours of the wretched weary tillers of the soil, leaving the valleys bare and mean by reason of the poverty which is left there.

C.A. 108 v. a

Among irremediable and destructive terrors the inundations caused by impetuous rivers ought to be set before every other awful and terrifying source of injury. But in what tongue or with what words am I to express or describe the awful ruin, the inconceivable and pitiless havoc, wrought by the deluges of ravening rivers, against which no human resource can avail?

C.A. 108 v. b

The movement of water within water proceeds like that of air within air.

C.A. 108 v. a

If a drop of water falls into the sea when this is calm, it must of necessity be that the whole surface of the sea is raised imperceptibly, seeing that water cannot be compressed within itself like air.

C.A. 20 r. a

The deluges of rivers are created when the mouths of the valleys cannot afford egress to the waters that they receive from these valleys as rapidly as the valleys receive them.

The progress of the water is swifter when it falls at a greater angle.

C.A. — (Nature of Water, 643)

Prove and draw up the rule for the difference that there is between a blow given by water upon water, and by water falling upon something hard; and consider well also that as water falls upon other water, and it yields space to the blow, the percussion making the water open as it receives the blow, so the same result will occur in a vase when the water which is contained within it has been struck, for it will be the same as when falling water has struck against a hard substance which resists the blow.

C.A. 153 v. d

So it is in a state of continual change, sometimes of position and sometimes of colour, now enclosing in itself new scents and savours, now keeping new essences or qualities, showing now life and now death, now setting in this place and now in that, now lending itself to produce and now taking away, now raising and now abasing, now speeding and now keeping still, now forming the cause and now the effect, now the beginning and now the end; it is an ever-flowing stream that enriches, and passing on makes itself a torrent, and destroys and enriches the rest.

Water is sometimes sharp and sometimes strong, sometimes acid and sometimes bitter, sometimes sweet and sometimes thick or thin, sometimes it is seen bringing hurt or pestilence, sometimes health-giving, sometimes poisonous. It suffers change into as many natures as are the different places through which it passes. And as the mirror changes with the colour of its subject, so it alters with the nature of the place, becoming noisome, laxative, astringent, sulfurous, salty, incarnadined, mournful, raging, angry, red, yellow, green, black, blue, greasy, fat or slim. Sometimes it starts a conflagration, sometimes it extinguishes one; is warm and is cold, carries away or sets down, hollows out or builds up, tears or establishes, fills or empties, raises itself or burrows down, speeds or is still; is the cause at times of life or death, or increase or privation, nourishes at times and at others does the contrary; at times has a tang, at times is without savour, sometimes submerging the valleys with great floods. In time and with water, everything changes.