by Aristotle
4 · Why are boys and women less liable to white leprosy than men, and old women more than young? Is it because white leprosy is due to the escape of breath, and the bodies of boys are dense and do not allow the passage of breath, and those of women do so less than those of men, for the breath is diverted into the menstrual [30] fluids? The density of their flesh is shown by its smoothness. But the bodies of middle-aged and old women allow the passage of breath; for they alone, like old buildings, have a loose structure of their component parts.
5 · Why is it that man alone has white leprosy? Is it because he is the [35] thinnest-skinned and at the same time the fullest of breath amongst the animals? An indication of this is the fact that leprosy appears most abundantly and soonest on the parts of the body where the skin is thinnest. Or, while this is true, is there a further reason, namely, that in man alone of the animals the hair turns grey? For in [891b1] leprosy the hair becomes grey, and so it is impossible for leprosy to occur in those in whom the hair does not turn grey.
6 · Why is it that goats and sheep yield the most milk, although their bodies are not the largest, whereas women and cows produce proportionately less? Is it [5] because in the latter two cases the available material is used up to form bulk, while in the other animals it goes into excretions, and in sheep and goats the residue of the excretion all becomes milk? Or is it because sheep and goats are more prolific than [10] the large animals, and so draw off more excretion, because they have more offspring to nourish? Or is it because owing to the weakness of their bodies more excretion is formed during the period of gestation, and the milk comes from the excretion?
7 · Why is it that in some animals (goats, for example) a change of water causes a change in their colour, which assimilates to that of other animals in the new locality, whereas with other animals (man, for example) this is not so? Or, to put [15] the question generally, why do some animals change and others not (the crow, for example)? Do those animals not change in whom the element of moisture does not predominate, birds, for example, which consequently have no bladder? Why is it that while such creatures do not themselves change, yet their offspring do so? Is it [20] because the offspring is weaker than its parents?
8 · Why are males usually larger than females? Is it because they are hotter, and heat is productive of growth? Or is it because the male is complete in all its parts, whereas the female is defective? Or is it because the male takes a long time to attain perfection, the female a short time?
[25] 9 · Why is it that some animals bear their young quickly, but in others the period of gestation is a long one? Is it because the longer-lived animals come to perfection more slowly? It is the longer-lived animals that take a long time to bear their young. This is not, however, true of the longest-lived of all animals; for example, the horse is slower in bearing its young but shorter-lived than man. The [30] reason for this is the hardness of the uterus; for the uterus of a mare may be compared to a dry soil which does not readily bring the crops to maturity.
10 · Why is it that the young of all other animals resemble their parents in nature more closely than do those of man? Is it because man’s mental condition is more varied at the moment of sexual intercourse, and so the offspring varies [35] according to the condition of the male and female parents? The other animals, or most of them, are wholly absorbed in the sexual act; further, owing to this avidity, impregnation does not usually take place.
[892a1] 11 · Why is it that fair men and white horses usually have grey eyes? Is it because there are three colors in eyes, black, greenish, and grey, and the colour of [5] the eyes follows that of the body, resulting in this case in greyness?
12 · For what reason are there dwarfs? Or to put the question more generally, why are some creatures quite large, others small? Let us examine the latter question. The causes of smallness are two, either space or nourishment-space, if it be narrow, and nourishment, if it be scanty; as happens when attempts [10] are made to make animals small after their birth, for example by keeping puppies in quail-cages. Those who suffer from lack of space become pygmies; for they have width and depth corresponding to the dimensions of their parents, but they are quite [15] small in stature. The reason for this is that owing to the narrowness of the space in which they are confined the straight lines become crushed and bent. So pygmies are like figures painted on shops which are short in stature but are seen to be of ordinary width and depth. Those who fail to come to perfection from lack of nourishment [20] clearly have the limbs of children, and one sometimes sees persons who are very small and yet perfectly proportioned, like Maltese lap-dogs. The reason is that the process of growth has a different effect from that of space.
13 · Why is it that some animals come into being from the sexual intercourse of animals with one another, others from the compounding of certain elements—a process resembling the original production of their species? Just as the [25] writers on natural phenomena explain the first origin of animals as being due to powerful changes and movements in the world and universe; so now, if it is to happen again, some similar movements must take place. For the beginning of anything is the most important part, being indeed half of the whole; and in this case [30] the seed is the beginning. The reason then why small animals which are not produced by sexual intercourse resemble the species as it originally came into being, is the smallness of the seed; for the smaller a thing is, the smaller is its first beginning. So the changes even of this are sufficient to produce a seed for it. And this is what actually happens; for it is under conditions of change that such [35] creatures usually come into being. In the larger animals a greater change is necessary for their production.
14 · Why is it that some animals are prolific, such as the pig, the dog, and the hare, whilst others are not so, for instance man and the lion? Is it because the [892b1] former class has a number of wombs which they desire to fill and moulds into which the semen is distributed, while with the latter the opposite is the case?
15 · Why has man a smaller distance between his eyes in proportion to his size than any other animal? Is it because man is the most natural of creatures and [5] perception is naturally of that which is in front, since it is necessary to see beforehand that to which the movement is directed? Now the greater the distance between the eyes, the more will the sight incline sideways. So if the sight is to accord with nature, the distance between the eyes ought to be as small as possible, for then [10] it will travel most directly forward. Further, the other animals must necessarily turn their gaze sideways, since they do not possess hands; their eyes therefore are farther apart, especially those of sheep, because they generally advance bending their heads downwards.
16 · Why is it that the other animals seldom or never emit semen during [15] sleep? Is it because no animal except man sleeps on its back and no emission of semen takes place except in that position? Or is it because the other animals dream less than man, and the emission of semen only takes place when the imagination is stirred?
17 · Why is it that some animals move their heads and others not? Is it [20] because some have no necks and so cannot move their heads?
18 · Why does man sneeze more than the other animals? Is it because in him the ducts are wide through which the breath and smells pass in? For it is with these, when they fill with breath, that he sneezes. That these ducts are wide is shown by the fact that man has a weaker sense of smell than any other animal; and the [25] narrower the ducts, the keener is the sense of smell. Since, therefore, the moisture, the evaporation of which causes sneezing, enters in larger quantities and more often into wide ducts, and man more than any other animal has such ducts, he might [30] naturally be expected to sneeze most often. Or is it because his nostrils are particularly short and so the heated moisture can quickly turn into breath, whereas in the other animals, owing to the length of their nostrils, it cools before it can evaporate?
19 · Why is it that in no animal is the tongue of a fatty consistency? Is it because that which is fat is dense,
whereas the tongue is naturally rare in order that [35] it may recognize different flavours?
20 · Why is it that females pass urine with an effort, but males without an effort? Is it because in the female the bladder is farther away both in depth of position and in distance, since the womb is situated between the fundament and the [893a1] bladder? It therefore requires a greater effort to drive the urine owing to the distance of the womb; and the requisite force is exercised by an effort of the breath.
21 · Why is it that all such animals as do not fly shed their winter coats, [5] except the pig? The dog, for example, does so, and the ox. Is it because the pig is very hot and its hairs grow out of a hot substance (for that which is fat is hot)? In the other animals the hair is shed because either the moisture cools or else the natural heat cannot concoct the nourishment. But the pig3 does not shed its hair, [10] either because the moisture in it undergoes no change or because its nourishment is properly concocted; for whenever any cause is present to make it shed its hair, the fat is sufficient to prevent it. Sheep and men are unaffected owing to the quantity [15] and density of their hair; for the cold cannot penetrate deep enough to congeal the moisture or to prevent the heat from concocting it.
22 · Why is it that in sheep the hair grows again softer when it is plucked out, but in man it is harder? Is it because the hair of sheep grows out of the surface, [20] and so can be plucked out without causing pain, the source of its nourishment, which is in the flesh, remaining unimpaired? So the pores being opened, the excretions evaporate more readily, and the wool receives the natural nourishment of the flesh, the latter being fed by soft, sweet nourishment. The hair of man, on the other hand, since it grows from a great depth, can only be plucked out by force and [25] painfully. This is shown by the fact that it draws blood with it. The place therefore from which it is plucked is wounded and scarred. So at last the hair ceases to grow on those who pluck it out, and as long as it does grow again, it grows hard, because all the nourishing food in the flesh fails, and it is from the excretions of this food [30] that the hair grows. This can be illustrated by the fact that in all those who inhabit a southerly clime the hair is hard, because the exterior heat penetrates deeply and vaporizes the well-concocted nourishment; but the hair of those who dwell in northern climes is soft, because in them the blood and sweet humours are nearer the surface, for which reason also they have a healthy complexion. [35]
23 · Why is it that in sheep the longer the hair grows the harder it is, whereas in man it is softer? Is it because the hair of sheep, obtaining the nourishment described above, receives less food because it is far removed from the source of it, and the nourishment already present in it easily evaporates out of it owing to the heat as a result of concoction? And as the hair dries it becomes harder;4 [893b1] for it is the moisture which makes it soft. Human hair, on the other hand, receives less nourishment but is situated nearer to the source of it; and the nourishment is more thoroughly concocted because it is less abundant, and, being concocted, it makes the hair softer, because anything that is concocted is softer than that which is [5] unconcocted; for human hair is derived more from excretion than that of sheep. This is shown by the fact that the wool of young sheep is softer than that of old.
24 · Why is it that thick-haired men and birds with thick feathers are [10] lustful? Is it because they are naturally hot and moist? Now both these characteristics are necessary for sexual intercourse; for the heat causes excretion, and the moisture is the form which the excretion takes. Lame men are lustful for the same reason; for, owing to the deficiencies of their legs, the nourishment is carried downwards in small quantities only, but travels into the upper region of the body in [15] large quantities, and is there converted into semen.
25 · Why has man no mane? Is it because he has a beard, and so the nourishment consisting of the necessary excretion, which in animals goes into the mane, in man goes to the jaws?
26 · Why is it that all animals have an even number of feet? Is it because it [20] is impossible to move (except by jumping), unless some part is at rest? Since, then, progression involves two things, namely, movement and rest, we immediately get here a pair and an even number. Quadrupeds have two more legs;5 for they move two, while the other two are at rest. Six-footed animals have an additional pair,6 of [25] which one moves while the other is at rest.
27 · Why is it that in horses and asses hair grows out of scars, but not in man? Is it because in the other animals the skin is part of the flesh, but in man it is only as it were a condition of the flesh? For in man the surface of the flesh seems to [30] become harder through cooling and resembles what we call the crust of boiled meal; just, then, as this crust is really only boiled meal, so what is called man’s skin would really be only flesh. Now when a man receives a wound or is chafed, the result is [35] that his flesh becomes denser; and so, the surface of the flesh having undergone a change, the wounded parts do not assume the same nature as the original skin; and, as the flesh has undergone a change, it is not to be wondered at that what grew from it no longer does so—a phenomenon also occurring in what is called baldness, which is also due to a corruption and change in the surface of the flesh. When, however, [894a1] beasts of burden have been chafed and recover again, the parts of the body affected fill out again with the same substance, but it is weaker than it was before; and since their skin too is a part of them, the hair (which grows out of the skin) must come [5] forth and grow, but it is white, because the skin which was formed is weaker than the original skin, and white hair is the weakest kind of hair.
28 · Why is it that among the other animals twins though differing in sex are just as likely to survive, but this is not so with the young of man? Is it because human twins are particularly weak, for man naturally produces only one offspring [10] at a time? Now in twins it is unnatural to find a diversity of sex; and so what is most contrary to nature is also weakest.
29 · Why is it that in horses and asses hair grows out of scars, but not in man? Is it because the scar impedes the growth of the hair, either owing to the condensation of the flesh or because its nutrition is impaired? In man, therefore, it [15] absolutely prevents the growth owing to the weakness of the hair; but in horses it does not prevent, but merely impairs, the growth.
30 · Why have animals an even number of feet? Is it because in anything that moves something must necessarily be at rest, and this could not happen if there were an odd number of feet (for7 it was the arrangement of the feet in pairs which [20] originally made movement possible)?
31 · Why is it that animals are asleep for a shorter time than they are awake, and their sleep is not continuous? Is it because all the excretion is not concocted at the same time, but, when some is concocted, the animal is relieved and wakes up? Again, they more often wake up when the region in which the excretion [25] is concocted becomes cold; for it quickly and frequently ceases to do its work, and this cessation causes awakening. Sleep not unnaturally8 seems to be pleasant, because it gives us rest; but the rest which we take in sleep does not last longer than the time taken by our natural activities, nor do we eat for a longer period than that during which we abstain from food, in spite of the fact that eating is pleasanter than fasting.
[30] 32 · Why is it that some animals imitate their parents immediately after birth, while others, like man, do so late, or hardly at all, or never? Is it because some quickly attain a state of physical perfection,9 while others are late in doing so, and some are without a perception of what is for their good, while others possess such a perception? Those therefore which possess both these qualities, namely, perception of what is for their good and physical perfection, imitate their parents, [35] but those who have not both these qualities do not do so; for physical and perceptive powers are both requisite.
33 · Why is it that white leprosy does not occur in animals other than man? Is it because, while it is a disease which afflicts other animals, only in man does the hair and skin turn partially white? (But, if so, one might ra
ise the question why [894b1] diversity of colour in animals occurs at birth and not afterwards.) Or is it because the skin of other animals is hard, whereas man has naturally very thin skin? Now white leprosy is an excretion of breath, which in the other animals is prevented from [5] escaping by the thickness of their skin.
34 · Why is it that in white leprosy the hair turns grey, but it does not necessarily follow that leprosy is always present where there is grey hair? Is it because the hair grows from the skin, and greyness is as it were a corruption of the hair? When therefore the skin is in a morbid condition, the hair that grows from it is [10] necessarily affected; but when the hair is unhealthy the skin is not necessarily so.
35 · Why is it that some animals are ill-tempered after bearing young, dogs, for example, and pigs, but others are not noticeably so, for instance women and sheep? Is it because those animals which are full of excretions are mild-tempered, for that which causes them pain passes out at the time of birth? Those,10 on the [15] other hand, who in bearing young lose healthy material, are made irritable by the reduced condition in which they are; just as hens are bad-tempered, not just when they have laid, but when they are sitting, from want of food.
36 · Why is it that eunuchs, when they are emasculated, in other respects change into the likeness of the female,—for they have the voice, the shrillness, and [20] the lack of articulation which characterize women, and so undergo a violent change, as do other animals when castrated (in bulls and rams, however, we find the horns assuming contrary forms, the reason being that their females have contrary kinds of horns, and so bulls when they are castrated grow larger horns and rams smaller horns)—in respect of size, however, alone eunuchs change into the likeness of the [25] male, for they become larger? Now size is characteristic of the male, for the female is smaller than the male. Or is it not after all a change into the likeness of the female rather than the male? For it is not a change in every dimension, but only in height, whereas the male is characterized by width and depth as well; for this is what his [30] full growth involves. Furthermore, as is the female to the male, so within the female sex is the maiden to the woman; for the latter has reached the full nobility of form, while the former has not yet done so. It is into the likeness of their nature then that the eunuch changes; for their growth is in height. So Homer well says,