by Aristotle
Men go grey on the temples first, because the back of the head is empty of [785a1] moisture owing to its containing no brain, and the fontanelle has a great deal of moisture, a large quantity not being liable to decay; the hair on the temples, however, has neither so little that it can concoct it nor so much that it cannot decay, [5] for this region of the head being between the two extremes is exempt from both states. The cause of greyness in man has now been stated.
5 · The reason why this change does not take place visibly on account of age in other animals is the same as that already given in the case of baldness; their brain is small and less fluid than in man, so that the heat required for concoction does not [10] altogether fail. Among them it is most clear in horses of all animals that we know, because the bone about the brain is thinner in them than in others in proportion to their size. A sign of this is that a blow on this spot is fatal to them—thus Homer also [15] has said: ‘where the first hairs grow on the skull of horses, and a wound is most fatal’.10 As then the moisture easily flows to these hairs because of the thinness of the bone, whilst the heat fails on account of age, they go grey. The reddish hairs go grey sooner than the black, redness also being a sort of weakness of hair and all [20] weak things ageing sooner.
It is said that cranes become darker as they grow old. The reason for this would be that their feathers are naturally finer than others and as they grow old the moisture in the feathers is too much to decay easily.
Greyness comes about by some sort of decay, and is not, as some think, a [25] withering. A sign is the fact that hair protected by hats or other coverings goes grey sooner (for the winds prevent decay and the protection keeps off the winds), and the fact that it is aided by anointing with a mixture of oil and water. For, though water [30] cools things, the oil mingled with it prevents the hair from drying quickly, water being easily dried up. That the process is not a withering, that the hair does not whiten as grass does by withering, is shown by the fact that some hairs grow grey from the first, whereas nothing springs up in a withered state. Many hairs also whiten at the tip, for there is least heat in the extremities and thinnest parts.
When the hairs of other animals are white, this is caused by nature, not by any [785b1] affection. The cause of the colours in other animals is the skin; if they are white, the skin is white, if they are dark it is dark, if they are piebald in consequence of a mixture of the hairs, it is found to be white in the one part and dark in the other. But [5] in man the skin is in no way the cause, for even white-skinned men have very dark hair. The reason is that man has the thinnest skin of all animals in proportion to his size and therefore it has not strength to change the hairs; on the contrary the skin itself changes its colour through its weakness and is darkened by sun and wind, [10] while the hairs do not change along with it at all. But in the other animals the skin, owing to its thickness, has the influence belonging to the soil in which a thing grows: that is why the hairs change according to the skin but the skin does not change at all in consequence of the winds and the sun. [15]
6 · Of animals some are uni-coloured (I mean by this term those of which the kind as a whole has one colour, as all lions are tawny; and this condition exists also in birds, fish, and the other classes of animals alike); others though many-coloured are yet whole-coloured (I mean those whose body as a whole has the same colour, as [20] a bull is white as a whole or dark as a whole); others are vari-coloured. This last term is used in two ways; sometimes the whole kind is vari-coloured, as leopards and peacocks, and some fish, e.g. the so-called ‘thrattai’; sometimes the kind as a whole is not so, but such individuals are found in it, as with cattle and goats and, among [25] birds, pigeons; the same applies also to other kinds of birds. The whole-coloured change much more than the uniformly coloured, both into the simple colour of another individual of the same kind (as dark changing into white and vice versa) and into both colours mingled. This is because it is a natural characteristic of the [30] kind as a whole not to have one colour only, the kind being easily moved in both directions so that the colours both change more into one another and are more varied. The opposite holds with the uniformly coloured; they do not change except by an affection, and that rarely; but still they do so change, for before now white [35] individuals have been observed among partridges, ravens, sparrows, and bears. This happens when the course of development is perverted, for what is small is easily [786a1] spoilt and easily moved, and what is developing is small, the beginning of all such things being on a small scale.
Change is especially found in those animals of which by nature the individual is whole-coloured but the kind many-coloured. This is owing to the water which [5] they drink, for hot waters make the hair white, cold makes it dark, an effect found also in plants. The reason is that the hot have more air than water in them, and the air shining through causes whiteness, as also in froth. As, then, skins which are white by reason of some affection differ from those white by nature, so also in the [10] hair the whiteness due to disease or age differs from that due to nature in that the cause is different; the latter are whitened by the natural heat, the former by the external heat. Whiteness is caused in all things by the vaporous air imprisoned in them. Hence also in all animals not uniformly coloured all the part under the belly is [15] whiter. For practically all white animals are both hotter and better flavoured for the same reason; the concoction of their nutriment makes them well-flavoured, and heat causes the concoction. The same cause holds for those animals which are uniformly-coloured, but either dark or white; heat and cold are the causes of the [20] nature of the skin and hair, each of the parts having its own special heat.
The tongue also varies in the simply coloured as compared with the varicoloured animals, and again in the simply coloured which differ from one another, as white and dark. The reason is that assigned before, that the skins of the vari-coloured are vari-coloured, and the skins of the white-haired and dark-haired [25] are white and dark in each case. Now we must conceive of the tongue as one of the external parts, not taking into account the fact that it is covered by the mouth but looking on it as we do on the hand or foot; thus since the skin of the vari-coloured animals is not uniformly coloured, this is the cause of the skin on the tongue being also vari-coloured.
[30] Some birds and some wild quadrupeds change their colour according to the seasons of the year. The reason is that, as men change according to their age, so the same thing happens to them according to the season; for this makes a greater difference to them than the change of age.
The more omnivorous animals are more vari-coloured to speak generally, and [786b1] this is what might be expected; thus bees are more uniformly coloured than hornets and wasps. For if the food is responsible for the change, we should expect varied food to increase the variety in the movements and in the residual matter of the food, from which come into being hairs and feathers and skins.
[5] So much for colours and hairs.
7 · As to the voice, it is deep in some animals, high in others, in others again well-pitched and in due proportion between both extremes. Again, in some it is loud, in others small, and it differs in smoothness and roughness, flexibility and [10] inflexibility. We must inquire then into the causes of each of these distinctions.
We must suppose then that the same cause is responsible for high and deep voices as for the change which they undergo in passing from youth to age. The voice is higher in all other animals when younger, but in cattle that of calves is deeper. We [15] find the same thing also in the male and female sexes; in the other kinds of animals the voice of the female is higher than that of the male (this being especially plain in man, for nature has given this faculty to him in the highest degree because he alone [20] of animals makes use of speech and the voice is the material of speech), but in cattle the opposite obtains, for the voice of cows is deeper than that of bulls.
Now the purpose for which animals have a voice, and what is voice and sound generally, has been stated partly in the treatise
on sensation, partly in that on the [25] soul. But since lowness of voice depends on the movement being slow and its highness on its being quick, there is a difficulty in knowing whether it is that which moves or that which is moved that is the cause of the slowness or quickness. For some say that what is much is moved slowly, what is little quickly, and that this is the cause of some animals having a deep and others a high voice. Up to a certain [30] point this is well said (for it seems to be rightly said in a general way that the depth depends on a certain amount of the air put in motion), but not altogether, for if this were true it would not be easy to speak both soft and deep at once, nor again both loud and high. Again, the depth seems to belong to the nobler nature, and in songs the deep note is better than the high-pitched ones, the better lying in superiority, [787a1] and depth of tone being a sort of superiority. But then depth and height in the voice are different from loudness and softness, and some high-voiced animals are loud-voiced, and in like manner some soft-voiced ones are deep-voiced, and the same applies to the tones lying between these extremes. And by what else can we [5] define these (I mean loudness and softness of voice) except by the large and small amount of the air put in motion? If then height and depth are to be decided in accordance with the distinction postulated, the result will be that the same animals will be deep- and loud-voiced, and the same will be high- and soft-voiced; but this is [10] false.
The reason of the difficulty is that the words ‘great’ and ‘small’, ‘much’ and ‘little’ are used sometimes absolutely, sometimes relatively to one another. Whether an animal has a great voice depends on the air which is moved being much absolutely, whether it has a small voice depends on its being little absolutely; but whether they have a deep or high voice depends on their being thus differentiated in [15] relation to one another. For if that which is moved surpasses the strength of that which moves it, what is moved must go slowly; if the opposite, quickly. The strong, then, on account of their strength, sometimes move much air and make the movement slow, sometimes, having complete command over it, make the movement swift. On the same principle the weak either move too much air for their strength [20] and so make the movement slow, or if they make it swift move but little because of their weakness.
These, then, are the reasons of these contrarieties, that neither are all young animals high-voiced nor all deep-voiced, nor are all the older, nor yet are the two [25] sexes thus opposed, and again that not only the sick speak in a high voice but also those in good bodily condition, and, further, that as men verge on old age they become higher-voiced, though this age is opposite to that of youth.
Most young animals, then, and most females set but little air in motion because of their want of power, and are consequently high-voiced, for a little air is [30] carried along quickly, and in the voice what is quick is high. But in calves and cows, in the one case because of their age, in the other because of their female nature, the part by which they set the air in motion is not strong; at the same time they set a [787b1] great quantity in motion and so are deep-voiced; for that which is borne along slowly is heavy, and much air is borne along slowly. And these animals set much in movement whereas the others set but little, because the vessel through which the breath is first borne has in them a large opening and necessarily sets much air in [5] motion, whereas in the rest the air is better dispensed. As their age advances this part which moves the air gains more strength in each animal, so that they change into the opposite condition, the high-voiced becoming deeper-voiced than they were, and the deep-voiced higher-voiced, which is why bulls have a higher voice than [10] calves and cows. Now the strength of all animals is in their sinews, and so those in the prime of life are stronger, the young being weaker in the joints and sinews; moreover, in the young they are not yet tense, and in those now growing old the tension relaxes; hence both these ages are weak and powerless for movement. And [15] bulls are particularly sinewy, even their hearts, and therefore that part by which they set the air in motion is in a tense state, like a sinewy string stretched tight. (That the heart of bulls is of such a nature is shown by the fact that a bone is actually found in some of them, and bones seek the nature of sinew.)
[20] All animals when castrated change to the female character, and utter a voice like that of the females because the sinewy strength in the principle of the voice is relaxed. This relaxation is just as if one should stretch a string and make it taut by hanging some weight on to it, as women do who weave at the loom, for they stretch [25] the warp by attaching stone weights to it. For in this way are the testes attached to the seminal passages, and these again to the blood-vessel which takes its origin in the heart near the organ which sets the voice in motion. Hence as the seminal [30] passages change towards the age at which they are now able to secrete the semen, this part also changes along with them. As this changes, the voice too changes, more indeed in males, but the same thing happens in females too, only not so plainly, the [788a1] result being what some call ‘bleating’ when the voice is uneven. After this it settles into a deep or high voice of the succeeding time of life. If the testes are removed the tension of the passages relaxes, as when the weight is taken off the string or the [5] warp; as this relaxes, the principle which moves the voice is loosened in the same proportion. This, then, is the reason why the voice and the form generally change to the female character in castrated animals; it is because the principle is relaxed upon [10] which depends the tension of the body; not that, as some suppose, the testes are themselves a knot of many principles, but small changes are the causes of great ones, not per se but when it happens that a principle changes with them. For the principles, though small in size, are great in potency; this, indeed, is what is meant by a principle, that it is itself the cause of many things without anything else being [15] higher than it.
The heat or cold also of their habitat contributes to make some animals of such a character as to be deep-voiced, and others high-voiced. For hot breath being thick causes depth, cold breath being thin the opposite. This is clear also in pipe-playing, [20] for if the breath of the performer is hotter, that is to say if it is expelled as by a groan, the note is deeper.
The cause of roughness and smoothness in the voice, and of all similar inequality, is that the part or organ through which the voice is conveyed is rough or [25] smooth or generally even or uneven. This is plain when there is any moisture about the trachea or when it is roughened by any affection, for then the voice also becomes uneven.
Flexibility and inflexibility depend on the softness or hardness of the organ, for what is soft can be regulated and assume any form, while what is hard cannot; thus [30] the soft organ can utter a loud or a small note, and accordingly a high or a deep one, since it easily regulates the breath, becoming itself easily great or small. But hardness cannot be regulated.
Let this be enough on all those points concerning the voice which have not been previously discussed in the treatise on sensation and in that on the soul. [788b1]
8 · With regard to the teeth it has been stated previously that they do not exist for a single purpose nor for the same purpose in all animals, but in some for nutrition, in others also for fighting and for vocal speech. We must, however, [5] consider it not alien to the discussion of generation to inquire into the reason why the front teeth are formed first and the grinders later, and why the latter are not shed but the former are shed and grow again.
Democritus has spoken of these questions but not well, for he assigns the cause [10] too generally without investigating the facts in all cases. He says that the early teeth are shed because they are formed in animals too early, for it is when animals are practically in their prime that they grow according to nature, and suckling is the cause he assigns for their being found too early. Yet the pig also suckles but does not [15] shed his teeth, and, further, all the saw-toothed animals suckle, but some of them do not shed any teeth except the canines, e.g. lions. This mistake, then, was due to his speaking generally without examining what happens in
all cases; but this is what we ought to do, for any one who makes any general statement must speak of all the particular cases.
Now we assume, basing our assumption upon what we see, that nature never [20] fails nor does anything in vain so far as is possible in each case. And it is necessary, if an animal is to obtain food after the time of taking milk is over, that it should have instruments for the treatment of the food. If, then, as Democritus says, this [25] happened about the time of reaching maturity, nature would fail in something possible for her to do. And, besides, the operation of nature would be contrary to nature, for what is done by violence is contrary to nature, and it is by violence that he says the formation of the first teeth is brought about. That this view then is not true is plain from these and other similar considerations.