Notebooks
Page 18
Every man at three years is half the full height he will grow to at last.101
There is a great difference in the length between the joints in men and boys. In man the distance from the shoulder joint to the elbow, and from the elbow to the tip of the thumb, and from one shoulder to the other, is in each instance two heads, while in a boy it is only one head; because Nature forms for us the size which is the home of the intellect before forming what contains the vital elements.
Remember to be very careful in giving your figures limbs that they should appear to be in proportion to the size of the body and agree with the age. Thus a youth has limbs that are not very muscular nor strongly veined, and the surface is delicate and round and tender in colour. In man the limbs are sinewy and muscular; while in old men the surface is wrinkled, rugged and knotty, and the veins very prominent.102
(b) The Anatomy and Movement of the Body
The human body is a complex unity within the larger field of nature, a microcosm wherein the elements and powers of the universe were incorporated. In order to study its structure Leonardo dissected corpses and examined bones, joints, and muscles separately and in relation to one another, making drawings from many points of view and taking recourse to visual demonstration since an adequate description could not be given in words. According to him such visual demonstrations gave ‘complete and accurate conceptions of the various shapes such as neither ancient nor modern writers have ever been able to give without an infinitely tedious and confused prolixity of writing and of time’. Moreover, there are not only the various points of view, the infinity of aspects to be considered, there are also the continuous successions of phases in movements. The circular movements of shoulder, arm, and hand, for instance, is suggestive of a pictorial continuity such as we may see on a strip of film.
The study of structure included that of function, of the manner in which actions and gestures were performed, how the various muscles work together in bending and straightening the joints; how the weight of a body is supported and balanced. Leonardo looked upon anatomy with the eye of a mechanician. Each limb, each organ was believed to be designed and perfectly adapted to perform its special function. Thus the muscles of the tongue were made to produce innumerable sounds within the mouth enabling man to pronounce many languages. In his time divisions between the various branches of anatomy did not exist. He investigated problems of physiology and embryology, and the systems of nerves and arteries. He anticipated the principle of blood circulation and prepared the ground for further analyses on many subjects.
You who say that it is better to watch an anatomical demonstration than to see these drawings, you would be right if it were possible to observe all the details shown in such drawings in a single figure, in which with all your cleverness you will not see or acquire knowledge of more than some few veins, while in order to obtain a true and complete knowledge of these, I have dissected more than ten human bodies, destroying all the various members and removing the minutest particles of the flesh which surrounded these veins, without causing any effusion of blood other than the imperceptible bleeding of the capillary veins. And as one single body did not suffice for so long a time, it was necessary to proceed by stages with so many bodies as would render my knowledge complete; this I repeated twice in order to discover the differences. And though you should have a love for such things you may perhaps be deterred by natural repugnance, and if this does not prevent you, you may perhaps be deterred by fear of passing the night hours in the company of these corpses, quartered and flayed and horrible to behold; and if this does not deter you, then perhaps you may lack the skill in drawing, essential for such representation; and if you had the skill in drawing, it may not be combined with a knowledge of perspective; and if it is so combined you may not understand the methods of geometrical demonstration and the method of estimating the forces and strength of muscles; or perhaps you may be wanting in patience so that you will not be diligent.
Concerning which things, whether or no they have all been found in me, the hundred and twenty books which I have composed will give verdict ‘yes’ or ‘no’. In these I have not been hindered either by avarice or negligence, but only by want of time. Farewell.103
How it is necessary for the painter to know the
inner structure of man
The painter who has a knowledge of the nature of the sinews, muscles, and tendons will know very well in the movement of a limb how many and which of the sinews are the cause of it, and which muscle by swelling is the cause of the contraction of that sinew; and which sinews expanded into most delicate cartilage surround and support the said muscle.
Thus he will in divers ways and universally indicate the various muscles by means of the different attitudes of his figures; and will not do like many who, in a variety of movements, still display the same things in the arms, the backs, the breasts, and legs. And these things are not to be regarded as minor faults.104
In fifteen entire figures there shall be revealed to you the microcosm on the same plan as before me was adopted by Ptolemy in his cosmography; and I shall divide them into limbs as he divided the macrocosm into provinces; and I shall then define the functions of the parts in every direction, placing before your eyes the representation of the whole figure of man and his capacity of movements by means of his parts. And would that it might please our Creator that I were able to reveal the nature of man and his customs even as I describe his figure.105
Remember, in order to make sure of the origin of each muscle to pull the tendon produced by this muscle in such a way as to see this muscle move, and its attachment to the ligaments of the bones. You will make nothing but confusion in demonstrating the muscles and their positions, origins and ends, unless you first make a demonstration of thin muscles after the manner of threads; and in this way you will be able to represent them one over the other as nature has placed them; and thus you can name them according to the limb they serve, for instance the mover of the tip of the big toe, and of its middle bone or of the first bone, etc. And when you have given this information you will draw by the side of it the true form and size and position of each muscle; but remember to make the threads which denote the muscles in the same positions as the central line of each muscle; and so these threads will demonstrate the shape of the leg and their distance in a plain and clear manner.106
Of the hand from within
When you begin the hand from within first separate all the bones a little from each other so that you may be able quickly to recognize the true shape of each bone from the palm side of the hand and also the real number and position in each finger; and have some sawn through lengthwise, so as to show which is hollow and which is full. And having done this replace the bones together at their true contacts and represent the whole hand from within wide open. The next demonstration should be of the muscles around the wrist and the rest of the hand. The fifth shall represent the tendons which move the first joints of the fingers. The sixth the tendons which move the second joints of the fingers. The seventh those which move the third joints of these fingers. The eighth shall represent the nerves which give them the sense of touch. The ninth the veins and the arteries. The tenth shall show the whole hand complete with its skin and its measurements; and measurements should also be taken of the bones. And whatever you do for this side of the hand you should also do for the other three sides—that is for the palmar side, for the dorsal side, and for the sides of the extensor and flexor muscles. And thus in the chapter on the hand you will give forty demonstrations; and you should do the same with each limb. And in this way you will attain thorough knowledge. You should afterwards make a discourse concerning the hands of each of the animals, in order to show in what way they vary. In the bear for instance the ligaments of the tendons of the toes are attached above the ankle of the foot.107
Weight, force, and the motion of bodies and percussion are the four elemental powers in which all the visible actions of mortals have their being and their end.108
After the demonstration of all the parts of the limbs of men and of the other animals you will represent the proper way of action of these limbs, that is in rising from lying down, in moving, running, and jumping in various attitudes, in lifting and carrying heavy weights, in throwing things to a distance, and in swimming; and in every action you will show which limbs and which muscles perform it, and deal especially with the play of the arms.109
As regards the disposition of the limbs in movement you will have to consider that when you wish to represent a man who for some reason has to turn backwards or to one side you must not make him move his feet and all his limbs towards the side to which he turns his head. Rather must you make the action proceed by degrees and through the different joints, that is those of the foot, the knee, the hips, and the neck. If you set him on the right leg, you must make his left knee bend inwards and his left foot slightly raised on the outside; and let the left shoulder be somewhat lower than the right; and the nape of the neck is in a line directly over the outer ankle of the left foot. And the left shoulder will be in a perpendicular line above the toes of the right foot. And always set your figures so that the side to which the head turns is not the side to which the breast faces, since nature for our convenience has made us with a neck which bends with ease in many directions as the eye turns to various points and the other joints are partly obedient to it.110
On the grace of the limbs
The limbs should be adapted to the body with grace and with reference to the effect that you wish the figure to produce. If you wish to produce a figure that shall look light and graceful in itself you must make the limbs elegant and extended, and without too much display of the muscles; and the few that are needed you must indicate softly, that is, not very prominently and without strong shadows; the limbs and particularly the arms easy, so that they should not be in a straight line with the adjoining parts. If the hips, which are the pole of a man, are placed so that the right is higher than the left, then let the right shoulder be lower than the left and make the joint of the higher shoulder in a perpendicular line above the highest prominence of the hip. Let the pit of the throat always be over the centre of the ankle of that foot on which the man is leaning. The leg which is free should have the knee lower than the other, and near the other leg. The positions of head and arms are infinitely varied and I shall therefore not enlarge on any rules for them. Let them, however, be easy and pleasing, with various turns and twists and the joints gracefully bent, that they may not look like pieces of wood.111
That is called simple movement in a man when he simply bends forward, or backwards, or to the side.112
That is called a compound movement in a man when some purpose required bending down and to the side at the same time. . . .113
Of human movement
When you wish to represent a man in the act of moving some weight reflect that these movements are to be represented in different directions. A man may stoop to lift a weight with the intention of lifting it as he straightens himself; this is a simple movement from below upwards; or he may wish to pull something backward, or push it forward or draw it down with a rope that passes over a pulley. Here you should remember that a man’s weight drags in proportion as the centre of his gravity is distant from that of his support, and you must add to this the force exerted by his legs and bent spine as he straightens himself.114
The sinew which guides the leg, and which is connected with the patella of the knee, feels it a greater labour to carry the man upwards in proportion as the leg is more bent; the muscle which acts upon the angle made by the thigh where it joins the body has less difficulty and less weight to lift, because it has not the weight of the thigh itself. And besides this its muscles are stronger being those which form the buttock.115
The first thing that the man does when he ascends by steps is to free the leg which he wishes to raise from the weight of the trunk which is resting upon this leg, and at the same time he loads the other leg with his entire weight including that of the raised leg. Then he raises the leg and places the foot on the step where he wishes to mount; having done this he conveys to the higher foot all the weight of the trunk and of the leg and leaning his hand upon his thigh, thrusts the head forward and moves towards the point of the higher foot, while raising swiftly the heel of the lower foot; and with the impetus thus acquired he raises himself up; and at the same time by extending the arm which was resting upon his knee he pushes the trunk and head upwards and thus straightens the curve of his back.116
Man and every animal undergoes more fatigue in going upwards than downwards, for as he ascends he bears his weight with him and as he descends he simply lets it go.117
A man, in running, throws less of his weight on his legs than when he is standing still. In like manner the horse, when running, is less conscious of the weight of the man whom it is carrying; consequently many consider it marvellous that a horse in a race can support itself on one foot only. Therefore we may say regarding weight in transverse movement that the swifter the movement, the less the weight towards the centre of the earth.118
How a man proceeds to raise himself to his feet when he is sitting on level ground.119
It is impossible that any memory can hold all the aspects and mutations of any limb of any animal. We shall demonstrate this by taking the hand for an example. Since every continuous quantity is divisible in infinitum the movement of the eye, which observes the hand, travels through a space, which is also a continuous quantity and there divisible in infinitum. And in every stage of the movement the aspect and shape of the hand varies when it is seen, and will continue to vary as the eye moves in a complete circle. And the hand in turn will act in a similar way as it is raised in its movement, that is to say it will travel through space which is a continuous quantity.120
There are [four] principal simple movements in the flexion performed by the joint of the shoulder, namely when the arm attached to the same moves upward or downwards or forward or backward. One might say, though, that such movements are infinite. For if we turn our shoulder towards a wall and describe a circular figure with our arm we shall have performed all the movements contained in the said shoulder. And, since [every circle is] a continuous quantity, the movement of the arm [has produced] a continuous quantity. This movement would not produce a continuous quantity were it not guided by the principle of continuation. Therefore, the movement of that arm has been through all the parts of the circle. And as the circle is divisible in infinitum the variations of the shoulder have been infinite.121
One and the same action seen from various places
One and the same attitude is shown in an infinite number of variations, because it can be viewed from an infinite number of places and these places are of a continuous quantity, and a continuous quantity is divisible into an infinite number of parts. Consequently every human action shows itself in an infinite variety of situations.122
The movements of man performed on one single occasion or for one single purpose are infinitely varied in themselves. This can be proved thus. Let us assume that a man strikes some object. Then I say that his stroke is made up of two states. Either he is lifting the thing which must descend in order to bring about the stroke, or this thing is already descending. Whichever may be the case, it is undeniable that the movement occurs in space and that space is a continuous quantity, and that every continuous quantity is divisible in infinitum. The conclusion is that every movement of the thing which descends is variable in infinitum.123
(c) Physiology
Where there is life there is heat; where there is heat there is movement of the watery humours.124
The cause which moves the water through its springs against the natural course of its gravity is like that which moves the humours in all the shapes of animated bodies.125
[With a drawing of the heart showing veins and arteries.]
O writer, with what words will you describe with a like perfection the whole arrangement of that of which the drawi
ng is here? For lack of knowledge you will describe it confusedly so as to convey but little perception of the true shapes of things; and deceiving yourself you believe that you can satisfy the listener completely when you speak of the figure of anything that has body and is surrounded by surfaces.
I recommend that you do not cumber yourself with words unless you are speaking to the blind, or if you wish to demonstrate to the ears with words rather than to the eyes of men speak of things of substance or of nature and do not busy yourself in making enter by the ears things which have to do with the eyes for in this you will be far surpassed by the work of the painter.
With what words can you describe this heart without filling a whole book? Yet the more detail you write concerning it the more you will confuse the mind of the hearer. And you will always need commentators or to go back to experience, and this with you is very brief and only deals with a few things as compared with the extent of the subject concerning which you desire complete knowledge.126
Of the human eye
The pupil of the eye changes to as many different sizes as there are differences in the degrees of brightness and obscurity of the objects which present themselves before it. . . . In this case nature has provided the visual faculty, when irritated by excessive light, with the contraction of the pupil and here nature works like one who, having too much light in his habitation, blocks up the window more or less according to necessity, and who, when night comes, throws open the whole of this window in order to see better. . . .