Notebooks (15 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
Lightness is not produced except in conjunction with weight, nor is weight produced without lightness. This may be shown: Let air be introduced under water by blowing a pipe, then this air will acquire lightness and the water will acquire weight from having beneath it the air which is a body thinner and lighter than itself. . . .
Levity and gravity are caused by immediate motion. Motion is created by heat and cold.
Motion is an incident created by inequality of weight and force. . . .
The motion of the elements arises from the sun.
The heat of the universe is produced by the sun.
The light and heat of the universe come from the sun and its cold and darkness from the withdrawal of the sun.
Every movement of the elements arises from heat and cold.
Gravity and levity are created in the elements.
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Weight comes into being when an element is placed above another element thinner than itself.
Weight is caused by one element having been drawn within another.
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Weight is caused by one element being situated in another; and it moves by the shortest line towards its centre, not by its own choice, not because the centre draws it to itself; but because the other intervening element cannot withstand it.
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Gravity, force, and accidental movement together with percussion, are the four accidental powers with which all the visible works of mortals have their existence and their end.
Gravity
Gravity is accidental power, which is created by movement and infused in bodies standing out of their natural position.
Heavy and Light
Gravity and Lightness are equal powers created by one element being transferred into the other; in every function they are so alike, that they may be named a single power. For they have merely variation in the bodies in which they are infused, and in the movement of their creation and deprivation.
That body is said to be heavy which being free directs its movement to the centre of the world by the shortest way.
That body is said to be light which being free flees from the centre of the world; and each is of equal power.
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The centre of every gravity
Every gravity weighs through the central line of the universe because it is drawn to this centre from all parts.
A central line of the universe is that which arises from the centre of the world and ends in the centre of gravity of every body.
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The centre of magnitude of bodies is placed in the middle of their length, width, and depth. The centre of accidental gravity of these bodies is placed in the middle of those parts which resist and balance one another. The centre of natural gravity is that which divides a body into two parts of equal weight and quantity.
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By the ninth of the second of the Elements which says that the centre of every suspended gravity stops below the centre of its support, therefore:—The central line is the name given to what one imagines to be the straight line from the thing to the centre of the world. The centre of all suspended gravity desires to unite with the central line of its support. And that suspended gravity which happens to be further removed from the central line of its support will acquire more force in excess of that of its natural weight. Now, in conclusion, I affirm that the water of the spiral eddy gives the centre of its gravity to the central line of its pole and every small weight that is added on one of its sides is the cause of its movement.
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2. FORCE AND WEIGHT88
Here one asks whether gravity is produced by itself or by force, or whether force is produced by itself or by gravity.
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What difference there is between force and weight
Force is spiritual essence which by accidental violence is united to weighty bodies, restraining them from following their natural inclination; and here although of short duration it often shows itself of marvellous power.
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Force and weight have much in common in all their powers, and they differ only in the motion of their birth and death. For weight simply dies with the arrival at its native place, but force is born and dies with every motion.
Weight is a power created by the motion that transports one element into another by means of force, and the length of its life corresponds to its effort to regain its native place.
Force is the product of dearth and profusion. It is the child of material motion and the grandchild of spiritual motion, and the mother and origin of weight. Weight is confined to the elements of water and earth, but force is unlimited; for by it infinite worlds can be set in motion if it were possible to make instruments by which this force could be generated.
The spirit of the sentient animals moves through the limbs of their bodies and when the muscles it has entered are responsive it causes them to swell, and as they swell they shorten and in shortening they pull the tendons that are joined to them. And from this arises the force and movement of human limbs. Consequently material movement springs from spiritual.
The quality and quantity of the force in man will have the power of giving birth to other force, and this will be greater in proportion as the movement is longer.
Weight and force together with the motion of bodies and percussion are the four powers of nature by which the human race in its marvellous and various works seems to create a second nature in this world; for by the use of such powers all the visible works of mortals have their being and their death.
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That force will be more feeble which is more distant from its source.
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What is Force?
Force I define as an incorporeal agency, an invisible power, which by means of unforeseen external pressure is caused by the movement stored up and diffused within bodies which are withheld and turned aside from their natural uses; imparting to these an active life of marvellous power it constrains all created things to change of form and position, and hastens furiously to its desired death, changing as it goes according to circumstances. When it is slow its strength is increased, and speed enfeebles it. It is born in violence and dies in liberty; and the greater it is the more quickly it is consumed. It drives away in fury whatever opposes its destruction. It desires to conquer and slay the cause of opposition, and in conquering destroys itself. It waxes more powerful where it finds the greater obstacle. Everything instinctively flees from death. Everything when under constraint itself constrains other things. Without force nothing moves. The body in which it is born neither grows in weight nor in form. None of the movements that it makes are lasting.
It increases by effort and disappears when at rest. The body within which it is confined is deprived of liberty. Often also by its movement it generates new force.
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Force is the same throughout and the whole is in every part of it.
Force is a spiritual energy, an invisible power which is imparted by violence from without to all bodies that are without their natural balance.
Force is nothing but a spiritual energy, an invisible power, which is created and imparted, through violence from without, by animated bodies to inanimate bodies, giving to these the similarity of life, and this life works in a marvellous way, constraining and transforming in place and shape all created things. It speeds in fury to its undoing and continues to modify according to the occasion.
Retardation strengthens, and speed weakens it.
It lives by violence and dies from liberty.
It transmutes and compels all bodies to a change of place and form.
Great power gives it great desire of death.
It drives away with fury whatever opposes its destruction.
Transmuter of various forms.
Always lives ill at ease with whoever holds it.
Always in opposition to natural desires.
It grows slowly from small beginnings and makes itself a terrible and marvellous power and by compression of itself constrains all things . . . it dwells in bodies which are out of their natural course and use . . . willingly it consumes itself.
Force is the same throughout and through all the body where it is generated.
Force is only a desire of flight.
Always it desires to weaken and to spend itself.
Itself constrained it constrains everybody.
Without it nothing moves.
No sound or voice is heard without it.
Its true seed lies in living bodies.
Weight is transmitted to the full by perpendicular resistance, and is all in every part of the resistance.
If an oblique resistance opposed to the weight be loosened and freed, it will make no resistance to the weight; on the contrary it will descend with it to ruin.
It is in the nature of weight to transmit itself of its own accord to the desired place.
Every part of force contains the whole—contrary to weight. Often they are victors one over the other.
They are of similar nature as regards pressure and the stronger overpowers the weaker. Weight does not change of its own accord, while force is always fugitive.
Weight is corporeal and force is incorporeal.
Weight is material and force is spiritual.
One desires flight from itself and death, the other seeks stability and permanence.
Often one generates the other.
If weight creates force, force is weight.
If weight conquers force, force is weight.
And if they are of equal strength they make long company.
If one is eternal the other is mortal.
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If you are on a boat, and you there exert your utmost force the boat will never move from its position unless the said force is greater in an obstacle outside the boat than that made within it. Again if you are all wrapped in a sack, and within it make efforts to move yourself, you will find it impossible to move from your place; but if you draw a foot out of the sack, and use it as a lever on the ground putting your head to the bottom of the sack, then you will draw it backwards.
The flame also does the same with its desire to multiply and extend itself in the bombard, for while it is entirely inside the bombard does not recoil. But when this flame strikes and pushes the resisting air while remaining united to that which pushes on the bottom, it is the cause that the bombard recoils; for that portion of the flame that strikes, not being able to find in the air that instant passage that it requires, throws its force upon the opposite side.
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3. MOVEMENT95
Definition of Movement
Direct movement is that which extends from one point to another by the shortest line.
Curved movement is that in which no direct movement is to be found in any part.
Spiral movement is composed of an oblique and curved line which is such that the lines drawn from the centre to the circumference are all found to be of various lengths. And it is of four kinds, convex spiral, plane spiral, concave spiral, and the fourth is columnar spiral.
Then there still is the circular movement made always around one point at an equal distance and this is called circumvolution. There are also the irregular movements which are infinite and are composed of a mixture of the aforesaid movements.
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Of movement in general
What is the cause of movement. What movement is in itself. What it is which is most adapted for movement. What is impetus; what is the cause of impetus; the medium in which it is created. What is percussion; what is its cause. What is rebound. What is the curve of straight movement and its cause.
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A point has no part; a line is the transit of a point; points are the boundaries of a line. An instant has no time. Time is made of movement of the instant, and instants are the boundaries of time.
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Of movement
I find that force is infinite together with time; and that weight is finite together with the weight of the whole globe of the terrestrial machine. I find that the stroke of indivisible time is movement, and that this movement is of many varieties, namely natural, accidental, and participating; and this participating movement ends in its greatest power when it changes from the accidental to the natural, that is in the middle of its course; and the natural is more powerful at the end than at any other place; the accidental is strongest in the third and weakest at the close.
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