Just as the stone thrown into the water becomes the centre and cause of various circles, and the sound made in the air spreads out in circles, so every body placed within the luminous air spreads itself out in circles and fills the surrounding parts with an infinite number of images of itself, and appears all in all and all in each part.50
Air
Its onset is much more rapid than that of water, for the occasions are many when its wave flees from the place of its creation without the water changing its position; in the likeness of the waves which the course of the wind makes in cornfields in May, when one sees the waves running over the fields without the ears of corn changing their place.51
The elements are changed one into another, and when the air is changed into water by the contact it has with its cold region this then attracts to itself with fury all the surrounding air which moves furiously to fill up the place vacated by the air that has escaped; and so one mass moves in succession behind another, until they have in part equalized the space from which the air has been separated, and this is the wind. But if the water is changed to air, then the air which first occupied the space into which the aforesaid increase flows must needs yield place in speed and impetus to the air which has been produced, and this is the wind.
The cloud or vapour that is in the wind is produced by heat and it is smitten and banished by the cold, which drives it before it, and where it has been ousted the warmth is left cold. And because the cloud which is driven cannot rise because the cold presses it down and cannot descend because the heat raises it, it therefore must proceed across; and I consider that it has no movement of itself, for as the said powers are equal they confine the substance that is between them equally, and should it chance to escape the fugitive is dispersed and scattered in every direction just as with a sponge filled with water which is squeezed so that the water escapes out of the centre of the sponge in every direction. So therefore does the northern wind become the origin of all the winds at one and the same time.52
That wind will be of briefer movement which is of more impetuous beginning; and this the fire has taught us as it bursts forth from the mortars, showing us the form and speed by the smoke which penetrates the air in brief and scattered motion. But fitful impetuosity of the wind is shown by the dust that it raises in the air in its various twists and turns. One perceives also between the chains of the Alps how the clashing together of the winds is caused by the impetus of various forces; one sees how the flags of ships flutter in different currents; how on the sea one part of the water is struck and not another; and the same thing happens in the piazzas and on the sandbanks of rivers, where dust is swept away furiously in one part and not in another. And since these effects show us the nature of their causes we can say with certainty that the wind which has the more impetuous origin will have the briefer movement; and this is borne out by the aforesaid experiment showing the brief movement of the smoke from the mouth of the mortar. And this arises from the resistance that the air makes on being compressed by the percussion of this smoke which in itself also suffers compression in offering resistance to the wind. But if the wind is of slow movement it will extend over a very long way in a straight course, because the air penetrated by it will not become condensed in front of it and will not thwart its movement, but will readily expand spreading its course over a very long space.53
4. EARTH, WATER, AIR, AND FIRE
Leonardo is here making the ascent of the Monte Rosa on a fine summer’s day with an intensely blue sky overhead. His desire is to peer into those upper regions which are beyond the atmosphere—the sphere of the Element of Fire. His surmise that they are regions of ‘immense darkness’ and that the blue colour of the sky is due to the reflection of light by small particles in the air is correct.
Of the colour of the atmosphere
I say that the blue which is seen in the atmosphere is not its own colour but is caused by warm humidity evaporated in minute and imperceptible atoms on which the solar rays fall rendering them luminous against the immense darkness of the region of fire that forms a covering above them. And this may be seen, as I myself saw it, by anyone who ascends the Monte Rosa, a peak of the Alps that divides France from Italy. . . .
There I saw the dark atmosphere overhead and the sun as it shone on the mountain was far brighter here than on the plains below because a smaller extent of atmosphere lay between the summit of the mountain and the sun. [See p. 310.]
As a further illustration of the colour of the atmosphere, we may take the smoke of old and dry wood, which as it comes out of the chimneys seems to be a pronounced blue when seen against a dark space. But as it rises higher and is seen against the luminous atmosphere it turns immediately to an ashen grey hue. And this happens because it no longer has darkness beyond it. . . . If the smoke comes from young green wood it will not assume a blue colour, because as it is not transparent and is heavily charged with moisture it will produce the effect of a dense cloud which takes distinct lights and shadows as though it were a solid body. The same occurs with atmosphere which excessive moisture renders white, while little moisture acted upon by heat renders it dark, of a dark blue colour. . . . If this transparent blue were the natural colour of the atmosphere it would follow that wherever a greater quantity of the atmosphere intervened between the eye and the element of fire the shade of blue would be deeper; as we see in blue glass and in sapphires, which are darker in proportion as they are thicker. But the atmosphere in such circumstances acts in exactly the opposite way, since where a greater quantity of it comes between the eye and the sphere of fire, there it appears much whiter. This happens towards the horizon. And the less the extent of atmosphere between the eye and the sphere of fire of so much the deeper blue does it appear, even when we are in the low plains. It follows therefore, as I say, that the atmosphere assumes this azure hue by reason of the particles of moisture which catch the luminous rays of the sun.54
Prove that the surface of (the sphere of) the air where it borders on the fire, and the surface of the (sphere of) fire where it ends are penetrated by the solar rays which transmit the images of the heavenly bodies, large when they rise and small when they are on the meridian.
Let a be the earth and ndm the surface of the air bordering on the sphere of fire; hfg is the orbit of the sun; then I say that when the sun appears on the horizon g its rays are seen passing through the surface of the air at a slanting angle—om; this is not the case at dk. And so it passes through a greater mass of air.55
Of the heat that is in the world
Where there is life there is heat, and where vital heat is, there is movement of vapour. This is proved inasmuch as we see that the element of fire by its heat always draws to itself damp vapours and thick mists as opaque clouds which it raises from seas as well as lakes and rivers and damp valleys; and these being drawn by degrees as far as the cold region, the first portion stops, because heat and moisture cannot exist with cold and dryness; and where the first portion stops, the rest settle, and thus one portion after another being added, thick and dark clouds are formed.
They are often wafted about and borne by the winds from one region to another, where by their density they become so heavy that they fall in thick rain; and if the heat of the sun is added to the power of the element of fire, the clouds are drawn up higher still and find a greater degree of cold, in which they form ice and fall in storms of hail. Now the same heat which holds up so great a weight of water as is seen to rain from the clouds, draws them from below upwards, from the foot of the mountains, and leads and holds them within the summits of the mountains, and these finding some fissures, issue continuously and cause rivers.56
As water flows in different ways out of a squeezed sponge, or air from a pair of bellows, so it is with the thin transparent clouds that are driven up on high through the reflection occasioned by the heat; the part which finds itself uppermost is that which first reaches the cold region and there halted by the cold and dryness awaits its companion. The par
t below ascending towards the part that is stationary treats the air that is in between as though it were a syringe, and this then escapes crosswise and downwards; it cannot go upwards because it finds the cloud so thick that it cannot penetrate it.
And for this reason all the winds that make war upon the earth’s surface descend from above, and when they strike upon the resisting earth they produce a movement of recoil, which as it tries to rise meets the descending wind, and thereby the ascent is constrained to break its natural order, and taking a transverse route pursues a violent course which grazes incessantly the surface of the earth.
And when the aforesaid winds strike upon the salt waters, then their direction becomes clearly visible, in the angle that is formed by the lines of incidence and of recoil; and from these result the proud and menacing and engulfing waves, of which one is the cause of the other.
As the natural warmth spread through the human limbs is driven back by the surrounding cold which is its opposite and enemy flowing back to the lake of the heart and the liver fortifies itself there, making of these its fortress and defence, so the clouds being made up of warmth and moisture, and in summer of certain dry vapours, and finding themselves in the cold and dry region, act after the manner of certain flowers and leaves which when attacked by the cold hoar-frost pressing cold together offer a greater resistance.
So these in their first contact with the cold air begin to resist and not to wish to pass further forward; the others below continue to rise; the part above being stationary proceeds to thicken; the warmth and dryness recede to the centre; the part above abandoned by the warmth begins to freeze or rather to dissolve; the clouds below continue to rise and press the warmth nearer to the cold; and thus the warmth being constrained to return to its primary element is suddenly transformed into fire and twines itself across the dry vapour, and in the centre of the cloud makes a great increase, and kindling within the cloud which has become cool it makes a noise that resembles that of water falling on boiling pitch or oil, or of molten copper when plunged into cold water; even so, driven out by its opposite it shatters the cloud that would withstand it and dashing through the air breaks and destroys everything that opposes it; and this is the thunderbolt.57
Where the flame cannot live no animal that
draws breath can live
The bottom part of the flame is the first origin of this flame and through it passes all its nutriment of fat; and it is of less heat than the rest of the flame, just as it is of less brightness; and it is blue in colour and here its nutriment is purged and disposed of. The other part has the brighter flame, but this is the first to come into existence when the flame is created and it is born in spherical shape, and after a span of life produces above itself a very small flame of radiant colour and shaped like a heart, with its point turned towards the sky; and this continues to multiply towards infinity by absorbing the substance that feeds it.
The blue flame is formed of spherical shape . . . and does not in itself form a pyramidal figure until it has warmed the surrounding air sufficiently; and the principal heat of this blue flame goes upwards in the direction where it is the natural desire of the blue flame to travel, that is the shortest way to the sphere of fire.
The colour of the blue flame does not move of itself. Nor does the nourishment given to the flame by the candle move of itself. The movement must therefore be generated by others. The generator of this movement is the air which rushes to refill the vacuum created by the air that had been previously consumed by the flame. The light generates vacuum, and the air runs to succour this vacuum.53
5. MICROCOSM AND MACROCOSM
The organic and inorganic worlds are both of similar nature and subject to the same natural laws. Man is a part of a world, a microcosm included in a macrocosm.
The Beginning of the Treatise on Water
Man has been called by the ancients a lesser world and indeed the term is well applied. Seeing that if a man is composed of earth, water, air, and fire, this body of earth is similar. While man has within himself bones as a stay and framework for the flesh, the world has stones which are the supports of earth. While man has within him a pool of blood wherein the lungs as he breathes expand and contract, so the body of the earth has its ocean, which also rises and falls every six hours with the breathing of the world; as from the said pool of blood proceed the veins which spread their branches through the human body, so the ocean fills the body of the earth with an infinite number of veins of water. . . .
In this body of the earth is lacking, however, the nerves, and these are absent because nerves are made for the purpose of movement; and as the world is perpetually stable, and no movement takes place here, nerves are not necessary. But in all other things man and the earth are very much alike.58
Explanation of the presence of water on the
summits of the mountains
I say that just as the natural heat of the blood in the veins keeps it in the head of man, and when the man is dead the cold blood sinks to the lower parts, and as when the sun warms the man’s head the amount of blood there increases and grows so much with other humours, that by pressure in the veins it frequently causes pains in the head; in the same way with the springs which ramify through the body of the earth and, by the natural heat which is spread through all the containing body, the water stays in the springs at the high summits of the mountains. And this water that passes through a pent-up conduit within the body of the mountain like a dead thing will not emerge from its low state because it is not warmed by the vital heat of the first spring. Moreover, the heat of the element of fire and by day the heat of the sun have power to stir up the dampness of the low places of the mountains and to draw them up in the same way as it draws the clouds and calls up their moisture from the bed of the sea.59
The same cause which moves the humours in all kinds of living bodies against the natural law of gravity also propels the water through the veins of the earth wherein it is enclosed and distributes it through small passages. And as the blood rises from below and pours out through the broken veins of the forehead, as the water rises from the lowest part of the vine to the branches that are cut, so from the lowest depth of the sea the water rises to the summits of mountains, where, finding the waves broken, it pours out and returns to the bottom of the sea. Thus the movement of the water inside and outside varies in turn, now it is compelled to rise, then it descends in natural freedom. Thus joined together it goes round and round in continuous rotation, hither and thither from above and from below, it never rests in quiet, either in its course or in its own nature. It has nothing of its own but seizes hold on everything, changing into as many different natures as there are different places on its course, acting just like the mirror which takes in as many images as there are things passing in front of it. So it changes continually, now as regards place, now as regards colour, now it absorbs new smells or tastes, now it detains new substances or qualities, now it brings death, now health, sometimes it mixes with air or lets itself be drawn on high by heat, and on reaching the cold region, the heat that guided it upward is squeezed by the cold. And as the hand presses the sponge under water where the water flowing out makes an inundation into the other water, so the cold presses the air that is mingled with water, making it flee in fury and drive the other air; this then is the cause of the wind.60
That which to the utmost admiration of those who contemplate it raises itself from the lowest depth of the sea to the highest summits of the mountains and pouring through the broken veins returns to the deep sea and again rises with swiftness and descends again, and so in course of time the whole element circulates. So from high to low, so passing in and out, now with natural movement, now with fortuitous movement it proceeds, together and united. So it goes ranging round in continual circulation after the manner of the water of the vine, which as it pours through its cut branches and falls upon its roots rises again through the passages and falling again returns in continual circulation.
Th
e water which sees the air through the broken veins of the high mountain summits is suddenly abandoned by the power which brought it there, and escaping from these forces resumes its natural course in liberty.
Likewise the water that rises from the low roots of the vine to its lofty head falls through the cut branches upon the roots and mounts anew to the place whence it fell.61
6. A SPIRIT AMID THE ELEMENTS: ITS LIMITATIONS
Of Spirits
We have said that the definition of a spirit is a power united to a body, because of itself it can neither rise nor take any kind of movement in space, and if you say that it does rise of itself this cannot be within the elements. For if the spirit is an incorporeal quantity, this quantity is called a vacuum, and the vacuum does not exist in nature; and granting that one were formed it would be immediately filled up by the rushing in of the element in which such a vacuum had been generated. Therefore, by the definition of weight, which says that gravity is an accidental power, created by one element being drawn or impelled towards another, it follows that any element without weight in one element acquires weight by passing into the element above it, which is lighter than itself. One sees that a part of water has neither gravity nor levity when merged in the other water, but will acquire weight if drawn up into the air; and if you were to draw the air beneath the water, then the water on finding itself above this air acquires weight, which weight it cannot support by itself, and hence its collapse is inevitable; and it will fall into the water at the spot where there is a vacuum. The same thing would happen to a spirit if it were amid the elements where it would continually generate a vacuum in whatever element it might find itself and for this reason it would be continually flying towards the sky until it had quitted those elements.
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