Notebooks (14 page)
Authors: Leonardo da Vinci,Irma Anne Richter,Thereza Wells
Tags: #History, #Fiction, #General, #European, #Art, #Renaissance, #Leonardo;, #Leonardo, #da Vinci;, #1452-1519, #Individual artists, #Art Monographs, #Drawing By Individual Artists, #Notebooks; sketchbooks; etc, #Individual Artist, #History - Renaissance, #Renaissance art, #Individual Painters - Renaissance, #Drawing & drawings, #Drawing, #Techniques - Drawing, #Individual Artists - General, #Individual artists; art monographs, #Art & Art Instruction, #Techniques
7. THE VAULT OF HEAVEN
According to ancient traditions, universally accepted in Leonardo’s time, the earth with its elements (compare p. 14
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was enclosed and surrounded by the heavenly world with bodies that were neither heavy, nor light, nor corruptible. Looking beyond the phenomena of this earth, Leonardo tried to apply similar methods of observation and deduction to the vault of heaven. He erected a sort of observatory by placing an optical instrument under the skylight of his roof and speculated on the nature of the moon
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was enclosed and surrounded by the heavenly world with bodies that were neither heavy, nor light, nor corruptible. Looking beyond the phenomena of this earth, Leonardo tried to apply similar methods of observation and deduction to the vault of heaven. He erected a sort of observatory by placing an optical instrument under the skylight of his roof and speculated on the nature of the moon
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Doubts arose in his mind regarding the Ptolemaic system. Did the sun revolve around the earth? On a page of mathematical notes he wrote in large letters ‘The sun does not move’
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In order to see the nature of the planets, open the roof and note at the base one planet singly: the reflected movement on this base will show the nature of this planet; but arrange that the base reflects only one at a time.
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Construct glasses in order to see the moon large.
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It is possible to find means whereby the eye does not see remote objects as much diminished as they are in natural perspective where they are diminished by reason of the convexity of the eye which necessarily intersects at its surface the pyramids of every image conveyed to the eye between spherical right angles.
But the method that I show here cuts these pyramids at right angles close to the surface of the pupil. The convex pupil of the eye takes in the whole of our hemisphere while this will show only a single star; but where many small stars transmit their images to the surface of the pupil those stars are extremely small; here only one star is seen but it will be large. And so the moon will be larger and its spots more distinct. You should place close to the eye a glass filled with water . . . for this water makes objects which are congealed in balls of crystalline glass appear as though they were without glass.
Of the eye. Of bodies less than the pupil of the eye that which is nearest to it will be least discerned by the eye. And from this experience it is made known to us that the power of sight is not reduced to a point. . . . But the images of the objects conveyed to the pupil of the eye are distributed on this pupil exactly as they are distributed in the air: and the proof of this is shown to us when we look at the starry sky without sighting more fixedly one star than another; the sky then appears all strewn with stars; and their proportions in the eye are the same as in the sky and likewise the spaces between them.
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Of the Moon
The moon has no light of itself, but so much of it as the sun sees it illuminates. And of that illuminated part we see as much as faces us. And its night receives as much light as our waters lend it as they reflect upon it the image of the sun, which is mirrored in all those waters that face the sun and the moon.
The surface of the waters of the moon and of our earth is always ruffled more or less, and this ruggedness is the cause of the expansion of numberless images of the sun which are reflected in the hills and hollows and sides and crests of the innumerable waves; that is in as many different spots on each wave as there are eyes in different positions to see them. This could not happen if the sphere of water which in great part covers the moon were uniformly spherical, for then there would be an image of the sun for every eye, and its reflections would be distinct and its radiance would always be spherical as is clearly shown in the gilded balls placed on the tops of high buildings. But if the gilded balls were rugged or composed of globules like mulberries which are a black fruit composed of minute balls, then each part of these little balls visible to the sun and to the eye will display to the eye the lustre produced by the reflection of the sun. And, thus, in one and the same body there will be seen many minute suns; and these often will blend at a long distance and appear continuous.
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Nothing light remains among less light things. Whether the moon has its seat within its elements or not. And if the moon has not its special seat like the earth in the midst of its elements, how is it that it does not fall in the midst of our elements? And if it is not in the midst of its elements and does not fall down, it must be lighter than all other elements. And if it is lighter than all other elements why is it solid and not transparent?
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Demonstration that the earth is a star
In your discourse you must prove that the earth is a star much like the moon, and the glory of our universe; and then you must treat of the size of various stars according to the authors.
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The sun does not move.*
The sun has substance, shape, motion, radiance, heat, and generative power: and these qualities all emanate from it without its diminution.
The sun has never seen any shadow.
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Praise of the sun
If you look at the stars without their rays (as may be done by looking at them through a small hole made with the extreme point of a fine needle and placed so as almost to touch the eye), you will see these stars to be so minute that it would seem as though nothing could be smaller; it is in fact the great distance which is the reason of their diminution, for many of them are very many times larger than the star which is the earth with the water. Think, then, what this star of ours would seem like at so great a distance, and then consider how many stars might be set in longitude and latitude between these stars which are scattered throughout this dark expanse. I can never do other than blame many of those ancients who said that the sun was no larger than it appears; among these being Epicurus; and I believe that he reasoned thus from the effects of a light placed in our atmosphere equidistant from the centre; whoever sees it never sees it diminished in size at any distance. . . . But I wish I had words to serve me to blame those who would fain extol the worship of men above that of the sun; for in the whole universe I do not see a body of greater magnitude and power than this, and its light illumines all the celestial bodies which are distributed throughout the universe. All vital force descends from it since the heat that is in living creatures comes from the soul (vital spark); and there is no other heat nor light in the universe. . . . And certainly those who have chosen to worship men as gods such as Jove, Saturn, Mars, and the like have made a very great error, seeing that even if a man were as large as our earth he would seem like one of the least of the stars which appears but a speck in the universe; and seeing also that men are mortal and subject to decay and corruption in their tombs.
The Spera and Marullo and many others praise the sun.*
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II. THE FOUR POWERS OF NATURE72
Weight, force, together with percussion, are to be spoken of as the producers of movement as well as being produced by it. Of these three accidental powers two have one and the same nature in their birth, their desire, and their end.
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Weight, force, a blow, and impetus are the children of movement because they are born from it. Weight and force always desire their death and each is maintained by violence. Impetus is frequently the cause why movement prolongs the desire of the thing moved.
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Gravity, force together with percussion are not only interchangeably to be called mother and daughters the one of the other and all sisters together, because they may all be produced by movement, but they are both producers and daughters of this movement; because without these within us movement cannot create, nor can such powers be revealed without movement.
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PLANS FOR A BOOK ON THEORETICAL MECHANICS
Deal first with weight [gravitation]
then with its supports [statics]
then with friction
then with motion [kinetics]
and lastly with percussion.
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First deal with weight, then with movement, which creates force, then with this force and lastly with the blow.
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Arrange that the book of the Elements of mechanics with its examples shall precede the demonstration of the movement and force of man and other animals and by means of these you will be able to prove all your propositions.
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Your Treatise on the movement of heavy bodies deals with heavy liquids, with air, and with the motions of fire. Compare the motion of this fire with the whirls in air and in water and you will find whirls in the fire which enable it to combine its revolutions. This experiment you will make with registers and with boiling waters.
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On Machines
Why nature cannot give the power of movement to animals without mechanical instruments, as is shown by me in this book on movement which nature has created in the animals. And for this reason I have drawn up the rules of the four powers of nature without which nothing can give local movement to these animals. We shall, therefore, first describe this local movement and how it produces and is produced by each of the three other powers. Then we shall describe the natural weight, for though no weight can be said to be other than accidental it has pleased us to style it thus in order to distinguish it from force, which in all its operations is of the nature of weight and is for this reason called accidental weight, and this is the force which is produced by the third power of nature, that is the inherent and natural power. The fourth and last power will be called percussion, that is the end and restraint of movement. And we shall begin by saying that every local insensible movement is produced by a sensible move, just as in a clock the counterpoise is raised up by man, who is its mover. Moreover the elements repel or attract each other, for one sees water expelling air from itself, and fire entering as heat under the bottom of a boiler and afterwards escaping in the bubbles on the surface of the boiling water. And again the flame draws to itself the air, and the heat of the sun draws up the water in the form of moist vapour which afterwards falls down in thick heavy rain. Percussion, however, is the immense power which is generated within the elements.
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1. WEIGHT80
Heat and cold proceed from the nearness or remoteness of the sun. Heat and cold cause the movement of the elements. No element has of itself weight or lightness. . . .
The motion originates from the fact that what is thinner can neither resist nor support what is more dense.
Lightness is born of weight and weight of lightness; and they give birth one to another at the same time; repaying in the same instant the boon of their creation they grow in power as they grow in life, and have more life as they have more motion; and they destroy one another in the same instant in the common vendetta of their death.
For so it is proved; lightness is not created unless it is joined to weight, nor is weight produced unless it is placed above lightness. Nor has lightness any existence unless it is underneath weight. . . .
And so it is with the elements. If for instance a quantity of air lay beneath water, the water would immediately acquire weight; not because it has itself changed, but because it does not meet with the due amount of resistance; it therefore descends into the position occupied by the air beneath it while the air fills up the vacuum which the weight has left.
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No element has weight or lightness unless it moves. The Earth is in contact with the Water and the Air and has of itself neither weight nor lightness. It has no consciousness of the Water and Air that surround it except when they happen to move. And this is shown by the leaves of plants which grow upon the earth in contact with water and air, and which do not bend except to the movement of air and water.
From this it follows that weight is an incident created by the movement of the lower elements in the higher.
Lightness is an incident created when the thinner element is drawn beneath the less thin . . . which then acquires weight and meets with insufficient resistance from the thinner element below which then acquires lightness.
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