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Generation of Animals

Generation of Animals

Book IV, 774b-776b

From: Aristotle: Generation of Animals (Greek). With an English translation by Arthur Leslie Peck, William Heinemann, London 1943, pp. 454-469.

Aristotle (384-322 BC) was a Greek philospher whose work proved enormously influential until the late Middle Ages. He wrote 'On the Generation of Animals' at around 350 AD.

same reason, too, men that are hairy are more prone to sexual intercourse and have more semen than men that are smooth. As for the hare, often some of its fetations are imperfect; others of its offspring, however, it brings to birth in a perfected state.

Among the Vivipara, some bring their young to birth in a perfect, some in an imperfect, state.To the former class belong the solid-hoofed and the. cloven-hoofed animals, to the latter most of the fissipede animals. The reason for this is that the solid-hoofed animals produce one at a birth, the cloven-hoofed animals produce "either one or two, in general,(a) and it is an easy matter to bring the nourishing of a few to completion. Those fissipede animals which produce their offspring in an imperfect state, all produce numerous offspring, and on that account while the fetations are quite young they are able to nourish them, but once they have advanced in growth and have attained some size their bodies are unable to bring the nourishing of them to completion, and so discharge them just as the larva-producing animals do,(b) for indeed their young, like the larvae, are practically unarticulated when born, e.g., those of the fox, the bear, the lion, and similarly with some of the others ; moreover, practically all of them are blind, e.g., the ones just mentioned, and in addition those of the dog, the wolf, and the jackal. The only animal which produces numerous offspring that are perfectly formed is the pig ; thus it is the only one which has a footing in both classes : (a) it produces numerous offspring, as the fissipede animals do, but (6) it is a species which is cloven-hoofed and solid-hoofed — for solid-hoofed pigs exist, as we know.(c) It produces numerous offspring because the nourishment available for


increase of size is secreted to yield seminal residue - since, for a solid-hoofed animal, the pig is not large in size ; at the same time and more commonly, it is cloven-hoofed, as though it were at odds with the nature of the solid-hoofed animals. On account of this, then, it not only produces sometimes one offspring, and two, but also and for the most part it produces numerous offspring, and it brings their nourishing to completion because of its fine physical condition : it is like a rich soil which can provide plants with sufficient and indeed abundant nourishment

The offspring of some of the birds also are hatched in an imperfect state, and blind(a); viz., of those which lay numerous eggs although they themselves are small in physique—e.g., the crow, the jay,(b) sparrows, and swallows(c) ; and of those birds which lay few eggs and yet do not provide in the egg abundant nourishment(d) for the chick-—e.g., the ring-dove, the turtle-dove, and the pigeon. And on this account, if the eyes of a swallow are deliberately put out while the bird is still young, they recover, because the injury is inflicted during the process of their formation and not after its completion ; that is why they grow and spring up afresh.(e) In general, then, the reason why offspring are born early before their formation is perfected, is because of inability to bring their nourishing to completion ; and the reason why they are born in an imperfect state is because they

viz., the young skin. This may happen many times in succession if the experiment is repeated. The connexion between regeneration and embryonic growth is well grasped by Aristotle, but there are of course some animals, such as the newts, where the power of regeneration is retained throughout adult life (cf. H.A. 508 b 4 ff.).


are born early. This is plain, indeed, in the case of seven months' children: in some of them, when they dare born, because they are imperfect, even the passages (e.g., those of the ears and nostrils) are often not yet fully articulated; as the child grows, however, they become articulated. Many such individuals survive.

In human beings, more males are born deformed than females; in other animals, there is no preponderance either way. The reason is that in human beings the male is much hotter in its nature than the female. On that account, male embryos tend to move about more than female ones,(a) and owing to their moving about they get broken more, since a young creature can easily be destroyed owing to its weakness. And it is due to this self-same cause that the perfecting of female embryos is inferior to that of male ones, (since their uterus is inferior in condition.(b) In other animals, however, the perfecting of female embryos is not inferior to that of male ones : they are not any later in developing than the males, as they are)(c) in women, for while still within the mother, the female takes longer to develop than the male does(d); though once birth has taken place everything reaches its perfection sooner in females than in males—e.g., puberty, maturity, old age—because females are weaker and colder in

(a) Cf. H.A. 584, a 26 ff.

(b) i.e. it is colder, because the nature of women is colder than that of other female animals, as is stated immediately above, and below ; cf. also 776 a 10, where women are said to be alone in suffering from uterine affections, again owing to lack of heat, resulting in inability' to concoct; and 775 a 30 ff.

(c) See app. crit. (d)Cf. H.A.. 583 b 22 ff.


their nature ; and we should look upon the female state as being as it were a deformity, though one which occurs in the ordinary course of nature.(a) While it is within the mother, then, it develops slowly on account of its coldness, since development is a sort of concoction, concoction is effected by heat, and if a thing is hotter its concoction is easy ; when, however, it is free from the mother, on account of its weakness it quickly approaches its maturity and old age, since inferior things all reach their end more quickly, and : this applies to those which take their shape under the hand of Nature just as much as to the products of the arts and crafts. The reason which I have just stated accounts also for the fact that (a) in human beings twins survive less well if one is male and the other female, but (6) in other animals they survive just as well : in human beings it is contrary to nature for the two sexes to keep pace with each other, male and female requiring unequal periods for their development to take place ; the male is bound to be late or the female early ; whereas in the other animals equal speed is not contrary to nature. There is also a difference between human beings and the other animals with regard to gestation. Other animals are most of the time in better physical condition, whereas the majority of women suffer discomfort in connexion with gestation. Now the cause of this is to some extent attributable to their manner of life, which is sedentary, and this means that they are full of residue; they have more of it than the other animals. This is borne out by the case of those tribes where the women live a life of hard work. With such women gestation is not so obvious, and they find delivery an easy business. And so do women everywhere who


are used to hard work. The reason is that the effort of working uses up the residues, whereas sedentary women have a great deal of such matter in their bodies owing to the absence of effort, as well as to the cessation of the menstrual discharges during gestation, and they find the pains of delivery severe, Hard work, on the other hand, gives the breath (pneuma) exercise, so that they can hold it (a); and it is this which determines whether delivery is easy or difficult. All these things, then, as we have said, are in their way factors producing the difference in gestation as between women and the other animals ; but the chief one is that whereas in some animals there is but little menstrual evacuation, and in others no visible evacuation at all, in women it is greater in volume than in any other animal; and the result of this is that when it is not being discharged owing to pregnancy it causes them trouble (and indeed even from pregnancy, when the menstrual discharge to take place diseases are the result) ; and most women are troubled in this way rather more at the beginning, just after they have conceived, because although the fetation is able to prevent the evacuation, yet as it is so small it does not at first use up any amount of the residue ; afterwards, when it does take up some of it, it relieves the trouble. In the other animals, however, as there is but little of it, its amount is just right for the growth of the embryos ; and as the residues which obstruct the nourishment get used up, the animals are in better physical condition. The same applies to water-animals, and to birds. The reason why some animals are no longer in good

is supplied by the holding of the breath." Cf. also M.A. 7d03 a 18, 9; P.A, 659 b 18, 667 a 29 ; and App. B §§22 ff.


physical condition when the fetations are becoming sizable is that the growth of the fetation needs more nourishment than that afforded by the residue. There are some few women who are in better physical condition during pregnancy. This occurs with those whose bodies contain but small amounts of residue, and as a result this is completely used up together with the nourishment that goes to th embryo.

We now have to treat of the mola uteri,(a) as it is called. This occurs in women occasionally only, but it does occur in some during pregnancy. They bring forth a " mola." It has been known to happen, in the case of a woman who has had intercourse and thinks she has conceived, that her figure, has increased to begin with, and all the rest has proceeded as expected, but when the time for her delivery was at hand, she has neither brought anything to birth nor yet has the size of her girth decreased; instead, she has continued in that condition for three or four years, till she was seized with dysentery which brought her to a dangerous pass, and then she has produced a fleshy mass, known as a" mola''. Sometimes, also, this condition lasts on into old age and persists until death. In such instances the objects which make their way out of the body are so hard that it is difficult to cut them in two even by means of an iron edge. Well, I have spoken in the Problems (b) of the cause of this occurrence; the case of the fetation in the womb is exactly the same as that of meat, when it is undercooked ; and it is due not to heat, as some people allege, but rather to weakness of heat (because it looks as though Nature in these cases suffers from

(b) This reference cannot be found.


some inability, and is unable to complete her work and to bring the process of formation to its consummation ; that is why the mola lasts on into old age or at any rate for a considerable time, for in its nature it is neither a finished product nor yet something wholly alien) ; since the cause of its hardness is the lack of concoction, just as underdone meat is another instance of lack of concoction.

But there is a puzzle here. Why is it that this phenomenon does not occur in the other animals ? (unless of course it does, but has entirely escaped observation). We must take the reason to be that alone of all animals women are liable to uterine affections ; they produce an excess of menstrual evacuations and cannot concoct them ; and so, when the fetation has been " set," formed out of a liquid which is difficult to concoct, then what is called the mola is produced ; and thus it is not surprising that this takes place chiefly in women if not exclusively in them.

Milk is produced towards the time of parturition in those female animals which are internally viviparous, and it is (1) of a useful and serviceable quality,(a) for Nature has provided animals with it so that they may nourish their young externally, and she has so arranged that it is neither deficient nor excessive in any way at that time ; this we actually observe to obtain unless some accident contrary to nature occurs. In the case of the other animals, as there is but a single period of gestation, the concoction of the milk coincides with that; in man, however, as there are more periods than one,(b) the milk must of necessity be available at the earliest of the possible dates; hence in women the milk, which is useless until seven months are up, at that point becomes useful and


is serviceable. But the fact that it is fully concocted at the final stages is due also (2) to another cause— the necessary cause, which is what we should expect, for, to begin with, the secretion of this particular residue is used up for the formation of the embryos; and in every animal the nourishment is the sweetest ingredient they possess and the most concocted, so that when this sweet substance is drawn off, what remains is bound to be briny and ill-savoured.(a) When, however, the fetations are approaching their completion, then there is more surplus residue, because less of it is being used up, and it is sweeter, since the well-concocted residue is no longer being drawn off to the same extent: it is no longer being expended upon the moulding of the embryo, but upon the small growth which it is making,(b) as though the embryo had by now, being completed, reached a stationary point (since a fetation, too, has its point ; of completion.) (c) That is why it makes its way out, and changes over to another process of formation as now possessing all that belongs to it, and it no longer takes what does not belong to it (d); and that is the time when the milk becomes serviceable. The milk collects in the upper part of the body, in the breasts, and this is accounted for by the original order of the body's construction. The part of the body above the diaphragm is the controlling part of the animal. (The part below is the place for the nourishment and the residue, in order that those animals which move about may have within them a

dent state of existence ; and even the wind has its γένεσις and φθίσις (778 a 2), where see note; and also cf. 737 b 9.

(d) This remark is obscure, and the sentence may be an interpolation. See the parallel passage, 777 a 22 ff.


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