Nature is here providing for perpetual adjustment and continual equilibrium by dilation and contraction of the pupil according to the obscurity or brightness which presents itself before it. You can observe the process in nocturnal animals such as cats, screech owls, long-eared owls, which have the pupil small at midday and very large at night . . . and if you wish to make the experiment with a man look intently at the pupil of his eye while holding a lit candle at a short distance away and make him look at this light as you bring it gradually nearer, and you will see that the nearer the light approaches to his pupil the more it will contract.127
The pupil is situated in the centre of the cornea [luce] which is of the shape of a part of a sphere which takes the pupil at the centre of its base. This luce forming part of a sphere takes all the images of the objects and transmits them through the pupil within to the place where the vision is formed.
In the anatomy of the eye, in order to be able to see the inside well without spilling its watery humour, you should place the whole eye in white of egg and make it boil and become solid; and then cut the egg and the eye transversely so that no part of the middle portion be poured out.128
Make two air holes in the horns of the great ventricles and insert melted wax by means of a syringe, making a hole in the ventricle of the memoria, and through this hole fill the three ventricles of the brain; and afterwards when the wax has set take away the brain and you will see the shape of the three ventricles exactly.129
(d) The Tongue
Of the muscles which move the tongue [illustrated by drawings]
No organ needs so great a number of muscles as the tongue,—of these twenty-four were already known apart from the others that I have discovered; and of all the members moved by voluntary action this exceeds all the rest in the number of its movements. . . . The present task is to discover in what way these twenty-four muscles are divided or apportioned in the service of the tongue in its necessary movements which are many and varied; and in addition it has to be seen in what manner the nerves descend to it from the base of the brain, and how they pass into this tongue distributing themselves and breaking into ramifications. And it must further be noted how these twenty-four muscles convert themselves into six in the formation they make in the tongue. Moreover, you should show whence these muscles have their origin, that is some in the vertebrae of the neck . . . some in the maxilla, and some on the trachea. . . . And similarly how the veins nourish them and how the nerves give them sensation . . . . The tongue works in the pronunciation and articulation of the syllables which constitute the words. This tongue is also employed during the necessary revolutions of the food in the process of mastication and in the cleansing therefrom of the inside of the mouth and teeth. Its principal movements are seven. . . .
Consider well how by the movement of the tongue, with the help of the lips and teeth, the pronunciation of all the names of things is known to us; and how the simple and compound words of a language reach our ears by means of this instrument; and how these, if there were a name for all the effects of nature, would approach infinity, together with the countless things which are in action and in the power of nature; and these man does not express in one language only but in a great number, and these also tend to an infinity; because they vary continually from century to century, and from one country to another, through the intermingling of the peoples who by wars and other mischances continually mix with one another; and the same languages are liable to pass into oblivion, and they are mortal like all created things; and if we grant that our world is everlasting, we shall say that these languages have been, and still will be, of infinite variety, through the infinite centuries which constitute infinite time. And this is not the case with any other sense; for these are concerned only with such things as nature continually produces; and the ordinary shapes of things created by nature do not change, as from time to time do the things created by man, who is nature’s greatest instrument.130
I have so many words in my mother-tongue that I ought rather to complain of the lack of a right understanding of things than of a lack of words with which fully to express the conception that is in my mind.131
(e) The Lips
Of the muscles which move the lips of the mouth
The muscles which move the lips of the mouth are more numerous in man than in any other animal; and this is necessary for him on account of the many actions in which these lips are continually employed, as in the four letters of the alphabet bfmp, in whistling, laughing, weeping, and similar actions. Also in the strange contortions used by clowns when they imitate faces.
What muscle is that which so tightens the mouth that its lateral boundaries come near together?
The muscles which tighten the mouth thus lessening its length are in the lips; or rather these lips are the actual muscles which close themselves. In fact this muscle alters the size of the lip below other muscles, which are joined to it and of which one pair distends it and moves it to laughter, . . . and the muscle which contracts it is the same of which the lower lip is formed; and a similar process goes on simultaneously in the upper lip. There are other muscles which bring the lips to a point; others that flatten them; others which cause them to curl back, others that straighten them; others which twist them all awry; and others which bring them back to the first position. So there always are as many muscles as correspond to the various attitudes of these lips and as many others that serve to reverse these attitudes; and these it is my purpose here to describe and represent in full, proving these movements by means of my mathematical principles.132
I once saw in Florence a man who had become deaf who, when you spoke very loud, did not understand you, but if you spoke gently and without making sound of the voice, understood merely from the movement of the lips. Now perhaps you will say that the lips of a man who speaks loudly do not move like those of one speaking softly, and that if they were to move them alike they would not be alike understood. As to this argument I leave the decision to experiment; make a man speak to you gently and note his lips.133
(f) The Embryo
Though human ingenuity may make various inventions answering by different machines to the same end, it will never devise an invention more beautiful, more simple, more direct than does Nature; because in her inventions nothing is lacking, and nothing is superfluous. She needs no counterpoise when she creates limbs fitted for movement in the bodies of animals, but puts within them the soul of the body which forms them, that is the soul of the mother which first constructs within the womb the shape of man, and in due time awakens the soul that is to be its inhabitant. And this at first lay dormant, under the tutelage of the soul of the mother who gives it nourishment and life through the umbilical vein with all its spiritual members; and this will continue as long as the said umbilical cord is joined to it by the secundines and the cotyledons by which the child is attached to the mother. These are the reasons why a wish, strong desire, a fright experienced by the mother is felt more powerfully by the child than by the mother; for there are many cases when the child loses its life from it. . . .134
As one mind governs two bodies, inasmuch as the desires, the fears, and the pains of the mother are one with the pains, that is the bodily pains, and desires of the child which is in the body of the mother, in like manner the nourishment of the food serves for the child and it is nourished from the same cause as are the other parts of the mother, and its vital powers are derived from the air which is the common living principle of the human race and of other living creatures.
The black races of Ethiopia are not the product of the sun; for if black gets black with child in Scythia, the offspring is black; but if a black gets a white woman with child the offspring is grey. And this shows that the seed of the mother has power in the embryo equally with that of the father.135
I reveal to men the origin of their second—second or perhaps first—cause of existence. Division of the spiritual from the material parts. And how the child breathes and how it is nouri
shed through the umbilical cord; and why one soul governs two bodies, as when one sees that the mother desires a certain food and the child bears the mark of it. And why the child [born] at eight months does not live. Here Avicenna contends that the soul gives birth to the soul and the body to the body and every member, but he is in error.*136
(g) Comparative Anatomy
You will represent here for comparison the legs of a frog, which have a great resemblance to the legs of man, both as regards bones and muscles. Then, in continuation, the hind legs of the hare which are very muscular, with strong active muscles, because they are not encumbered with fat.137
Note on the bendings of joints and on the way the flesh swells in their flexions or extensions; and of this most important study write a separate treatise: the description of the movements of animals with four feet; among which is man, who likewise in his infancy crawls on all fours.138
The walking of men is always after the universal manner of walking of animals with four legs inasmuch as just as they move their feet crosswise after the manner of the trot of the horse, so man moves his four limbs crosswise; that is if he puts forward his right foot in walking he with it puts forward his left arm and vice versa, invariably.139
The frog instantly dies when the spinal cord is pierced; and before this it lived without head, without heart or any bones or intestines or skin, and here therefore it would seem lies the foundation of movement and life. All the nerves of the animals derive from here: when this is pricked they instantly die.140
I have found in the composition of the human body that the organs of sense are duller and coarser as compared with those of the constitutions of animals. Thus it is composed of an instrument less ingenious and of parts less capable of receiving the power of the senses. I have seen in the Lion tribe how the sense of smell forming part of the substance of the brain descends down the nostrils which form a large receptacle for the sense of smell. This enters among a great number of cartilaginous cells with many passages leading up to the above-mentioned brain. The eyes in the Lion tribe have a large part of the head for their sockets and the optic nerves are in immediate communication with the brain; with men the contrary is seen to be the case for the sockets of the eyes occupy but a small part of the head, and the optic nerves are thin and long and weak; and by the weakness of their action we see by day, but badly at night; whereas the aforesaid animals see better by night than by day; and the proof of this is seen in the fact that they prowl for prey by night and sleep by day as do also nocturnal birds.141
The eyes of animals
The eyes of all animals have their pupils adapted to dilate and diminish of their own accord in proportion to the greater or less light of the sun, or other luminary. But in birds the variation is much greater and especially with nocturnal birds of the owl species such as the horned owl, the white and the brown owls. With these the pupil dilates until it almost occupies the whole eye, or diminishes to the size of a grain of millet, preserving always its circular shape.
But in the Lion tribe such as panthers, leopards, ounces, tigers, wolves, lynxes, Spanish cats, and other similar animals, the pupil as it diminishes changes from the perfect circle to an elliptical figure.
Man, however, having a more feeble sight than any other animal is less hurt by excessive light and his pupil undergoes less increase in dark places. But in the eyes of the above-mentioned nocturnal animals, in the horned owl, which is the largest nocturnal bird, the power of vision is so much increased that in the faintest glimmer of night (which we call darkness) it can see more distinctly than we in the splendour of noon, when these birds stay hidden in dark places; or if they are compelled to come out into the sunlit air the pupil contracts so much that their power of sight diminishes together with the quantity of the light.
Study the anatomy of the various eyes and see which are the muscles which open and close the said pupils of the eyes of animals.142
If at night your eye is placed between the light and the eye of a cat, it will see the eye look like fire.143
When the bird closes its eye with its two coverings it first closes the secondina, and this it does sidewards from the lachrymal gland towards the outer corner of the eye, and the outer covering closes from below upwards. And these two movements intersect and first cover the eye from the direction of the lachrymal gland because the bird has already seen that it is safe in front and below; it reserves only the upper part of the eye because of the dangers from birds of prey descending from above and behind; and it will first uncover the membrane in the direction of the outer corner, for if the enemy comes behind the bird has opportunity of flying forward. Also if it keeps the membrane called secondina which is of transparent texture it does so because if it did not possess this shield it could not keep its eyes open against the wind which strikes the eye in the fury of its swift flight.144
Analyse the movement of the tongue of the woodpecker.145
Describe the tongue of the woodpecker and the jaw of the crocodile.146
After an artist had mastered anatomy he was at liberty to create organisms according to his own ideas. He might, for instance, fit together parts of different animals to form a chimerical structure. Leonardo’s monsters are a curious instance of the way in which his mind united science and fantasy. They are usually either ideas for masquerades or emblems.
How to make an imaginary animal appear natural
You know that you cannot make any animal without it having its limbs such that each bears some resemblance to that of some one of the other animals. If therefore you wish to make one of your imaginary animals appear natural—let us suppose it to be a dragon—take for its head that of a mastiff or setter, for its eyes those of a cat, for its ears those of a porcupine, for its nose that of a greyhound, with the eyebrows of a lion, the temples of an old cock and the neck of a water-tortoise.147
(h) Draperies
The draperies thin, thick, new, old, with folds broken and pleated, soft light, shadows obscure and less obscure, with or without reflections, definite or indistinct according to distances and colours; and the garments according to the rank of those who wear them, long or short, fluttering or stiff according to the movements; so encircling the figures as to bend or flutter with ends streaming upwards or downwards, according to the folds; clinging close to the feet or separated from them, according as the legs within are shown at rest or bending, or twisting or striding; fitting closely or separating from the joints, according to the step or movement or whether the wind is represented.
And the folds should correspond to the quality of the draperies whether transparent or opaque. . . .
On the thin clothes of the women in walking, running, and jumping, and their variety.148
How draperies should be drawn from nature: that is to say, if you want to represent woollen cloth draw the folds from that, and if it is to be silk, or fine cloth or coarse, or linen or crape, vary the folds in each and do not represent dresses, as many do, from models covered with paper or thin leather which will deceive you greatly.149
Everything by nature tends to remain at rest. Drapery of equal density and thickness has a tendency to lie flat; therefore when you give it a fold or plait forcing it out of its flatness, note the effect of the restraint in the part where it is strongest; and the part farthest away from the restraint will be seen to relapse most into the natural state; that is to say it spreads out freely.150
You must not give to drapery a great confusion of many folds, but rather introduce only those held by the hands or arms; the rest you may let fall simply where its nature makes it flow; and do not let the nude forms be traversed by too many lines and broken folds.151
Figures dressed in a cloak should not show the shape so much that the cloak looks as if it were next to the flesh. For surely you would not wish that the cloak should be next to the flesh since you must realize that between the cloak and the flesh are other garments which prevent the shapes of the limbs from being visible and appearing through the cloak. A
nd those limbs which you show make thick of their kind so that there may seem to be other garments under the cloak. The limbs of a nymph or an angel should be shown in almost their original state, for these are represented clad in light draperies, which are driven and pressed against the limbs of the figures by the blowing wind.152
(i) Botany
The following pages contain a selection of Leonardo’s notes on plants. Other notes relating to landscape, such as studies of the formation of rocks, the movements of water and clouds, are given in Chapter II. Notes on atmosphere, light, and colour in landscape are given in Chapter IV, pp. 126 ff.
Numerous drawings of trees and flowering plants indigenous to Italy are to be found in his manuscripts. He was interested in the influence of sunlight and water on their growth. He watched the process of ripening of a gourd (see p. 344). He observed the gravitational attraction of the earth on certain plants (geotropism) and the habit of others to turn towards the sun (heliotropism). He examined the sap of trees and discovered that their age corresponds to the number of rings in the cross-sections of the stems. His observation of the order according to which the leaves occupy various positions on the stem or axis was a first step in establishing the laws of phyllotaxis which were developed centuries later.
He is not universal who does not love equally well all that is comprised in Painting. Someone for instance who does not care for landscapes and esteems them a matter involving merely cursory and simple investigations. So does our Botticelli, who said that such studies are vain since by merely throwing a sponge soaked with different colour at a wall a stain is formed wherein a lovely landscape might be discerned. I admit as quite true that in such a stain one might detect various inventions if one looks for them, like heads of men, different animals, battles, rocks, seas, clouds, trees, and the like, just as in listening to the chimes of bells one seems to hear whatever one chooses. But although such stains may suggest to you compositions, they do not teach you how to complete any detail.
Notebooks Page 19