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Letter to Women

Generation of Animals

Book IV, 765b-767b

From: Aristotle: Generation of Animals (Greek). With an English translation by Arthur Leslie Peck, William Heinemann, London 1943, pp. 386-401.

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.

semen to take shape or to discharge it. And (2) all concoction works by means of heat. Assuming the truth of these two statements, it follows of necessity that (3) male animals are hotter than female ones, since it is on account of coldness and inability that the female is more abundant in blood in certain regions of the body. And this abundance of blood is a piece of evidence which goes to prove the opposite of the view held by some people, who suppose that the female must be hotter than the male, on account of the discharge of menstrual fluid : blood, they argue, is hot, so that which has more blood in it is hotter. They suppose, however, that this condition occurs owing to excess of blood and heat, as though it were possible for anything and everything to be equally blood if only it is fluid and bloodlike in colour, without allowing for the possibility of its becoming less in quantity and purer in animals that are well-nourished. They apply the same standard here as they do to the residue in the intestine : if there is more of it they imagine that is a sign of a hotter nature. Yet in fact the opposite is the truth. Take a parallel case, that of fruit. Here the nourishment in its first stage is large in quantity,(a) but the useful product resulting from it through the various stages of its treatment is small, and in the end the final result is nothing in proportion compared with the original bulk. So too in the body, the various parts receive the nourishment in turn at the different stages of its treatment, and the final product resulting from all that amount of nourishment is quite small. In some, this is blood ; in others, its counterpart.

Now as the one sex is able and the other is unable


to secrete the residue in a pure condition ; and as here is an instrument for every ability or faculty, for the one which yields its product in a more finished condition and for the one which yields the same product in a less finished condition ; and as male and female stand opposed in this way (" able " and " unable " being used in more senses than one (a) ; therefore of necessity there must be an instrument (b) both for the male and for the female ; hence the male has the perineos (c) and the female has the uterus. Nature gives each one its instrument simultaneously with its ability, since it is better done thus. Hence each of these regions of the body gets formed simultaneously with the corresponding secretions and abilities, just as the ability to see does not get perfected without eyes, nor the eye without the ability to see, and just as the gut and the bladder are perfected simultaneously with the ability to form the residues. Now as the stuff out of which the parts are formed is the same as that from which they derive their growth,(d) namely the nourishment, we should expect each of the parts to be formed out of that sort of material and that sort of residue which it is fitted to receive. Secondly, and on the contrary, it is, as we hold, formed in a way out of its opposite. Thirdly, in addition, it must be laid down that, assuming the extinction of a thing means its passing into its opposite condition, then also that which does not get mastered by the agent which is fashioning it must of necessity change over into its opposite condition.(e) With these

(d) For this distinction between the grades of nourishment, see 744 b 32 ff.

(e)This is explained at length at 768 a 1 ff. The whole of the present passage should be read in conjunction with the later and fuller discussion. See also 766 b 15 ff.


as our premisses it may perhaps be clearer why and by what cause one offspring becomes male and another female. It is this. When the " principle " (a) is failing to gain the mastery and is unable to effect concoction owing to deficiency of heat, and does not succeed in reducing the material into its own proper form,(b) but instead is worsted in the attempt, then of necessity the material must change over into its opposite condition.(c) Now the opposite of the male is the female, and it is opposite in respect of that whereby one is male and the other female.(d) And since it differs in the ability it possesses, so also it differs in the instrument which it possesses. Hence this is the condition (e) into which the material changes over. And when one vital part changes (f) the whole make-up of the animal differs greatly in appearance and form. This may be observed in the case of eunuchs ; the mutilation of just one part of them results in such a great alteration of their old semblance, and in close approximation to the appearance of the female. The reason for this is that some of the body's parts(g) are " principles," and once a principle has been " moved " (i.e., changed), many of the parts which cohere (h) with it must of necessity change as well.

Let us assume then (1) that " the male " is a principle and is causal in its nature ;

(2) that a male ultimate is male in virtue of a particular ability, and a female is female in virtue of a particular inability ; (3) that the line of determination between the ability and the inability is whether a thing effects or does not effect

that the sexual parts, as distinct from the sexes, are " principles " ; but his position is made clear by the passage N766 b 2 ff.

(h) " Are of a piece with it " : cf, 764 b 24, 25.


concoction of the ultimate nourishment (in blooded animals this is known as blood, in the bloodless ones it is the counterpart of blood) ; (4) that the reason for this lies in the " principle," i.e., in the part of the body which possesses the principle of the natural wheat. From this it follows of necessity that, in the blooded animals, a heart must take shape and that the creature formed is to be either male or female and, in the other kinds (a) which have male and female sexes, the counterpart of the heart. As far, then, as the principle and the cause of male and female is concerned, this is what it is and where it is situated ; a creature, however, really is male or female only from the time when it has got the parts by which female differs from male, because it is not in virtue of some casual part that it is male or female, any more than it is in virtue of some casual part that it can see or hear.(b)

To resume then (c) : We repeat that semen has been posited to be the ultimate residue of the nourishment. (By "ultimate" I mean that which gets carried to each part of the body—and that too is why the offspring begotten takes after the parent which has begotten it, since it comes to exactly the same thing whether we speak of being drawn from every one of the parts or passing into every one of the parts, though the latter is more correct.(d) ) The semen of the male, however, exhibits a difference,

(c)The following paragraph is a short 765 b 8—766 b 7. (For the use of υηόκειται with participle, cf 778 b 17  τοιόνδε  ζωον νπόκειτι  ον .)

(d) See Bk. I. 721 b 13 ff., and especially the conclusion of   that discussion, 725 a 21 ff.


in as much as the male possesses in itself a principle of such a kind (a) as to set up movement [in the animal as well] and thoroughly to concoct the ultimate nourishment, whereas the female's semen contains material only. If (the male semen) gains (b) the mastery, it brings (the material) over to itself; but if it gets mastered, it changes over either into its opposite or else into extinction. And the opposite of the male is the female, which is female in virtue of its inability to effect concoction, and of the coldness of its bloodlike nourishment. And Nature assigns to each of the residues the part which is fitted to receive it. Now the semen is a residue, and in the hotter of the blooded animals, i.e., the males, this is manageable in size and amount,(c) and therefore in males the parts which receive this residual product are passages ; in females, however, on account of their failure to effect concoction, this residue is a considerable volume of bloodlike substance, because it has not been matured; hence there must of necessity be here too some part fitted to receive it, different from that in the male, and of a fair size. That is why the uterus has these characteristics ; and that is the part wherein the female differs from the male.(d)

We have now stated the cause why some creatures are formed as males, others as females.

And our statements are borne out by the facts. Thus : Young parents, and those which are older too, tend to produce female offspring rather than parents

it is all one whether we say "the semen" or the movement which causes the growth of each of the parts," or " the movement which originally sets and constitutes the fetation." Cf. 771 b 19 ff.

(c) Because it is more compact; see above, 765 b 3.

(d) Cf, 738 b 35 ff.


which are in their prime ; the reason being that in the young their heat is not yet perfected, in the older, it is failing. Also, parents which are more fluid of body and feminine tend to produce females ; this is true also of fluid semen as opposed to that which has " set " ; all these things are due to a deficiency of natural heat.

Also, the fact that when the wind is in the north(a) male offspring tend to be engendered rather than when it is in the south (is due to the same cause : animals' bodies are more fluid (b) when the wind is in the south) so that they are more abundant in residue as well. And the more residue there is, the more difficulty they have in concocting it; hence the semen of the males and the menstrual discharge of the women is more fluid.

Also, the fact that the menstrual discharge in the natural course tends to take place when the moon is waning (c) is due to the same cause. That time of month is colder and more fluid on account of the waning and failure of the moon (since the moon makes a summer and winter in the course of a month just as the sun does in the course of the whole year. [This is not due to its turning at the tropics ; no, the one occurs when the moon's light is increasing, the other when it is waning.(d)]). Also, shepherds say that it makes a difference so far as the generation of males and females is concerned not only whether copulation occurs when the wind is in the north or in the south, but also whether

that whereas summer and winter result from the " turnings " of the sun, viz., the solstices, the " summer " and " winter " of the moon are not due to the moon's " turnings," but to its waxings and wanings, which are completely independent of its " turnings."


the animals face north or south while they are copulating (a) : such a small thing thrown in on one ' side or the other (so they say) acts as the cause of heat and cold, and these in turn act as the cause of generation.

Male and female, then, differ generally with regard importance to each other in respect of the generation of male and of female offspring on account of the causes which have been stated. At the same time, they must stand in a right proportional relationship to one another,(b) since everything that is formed either by art or by nature exists in virtue of some due proportion. Now if " the hot " is too powerful it dries up fluid things ; if it is very deficient it fails to make them " set " ; what it must have in relation to the object which is being fashioned, is the mean proportional, and unless it has that, the case will be the same as what happens when you are cooking : if there is too much fire it burns up your meat, if there is too little it will not cook it—either way what you are trying to produce fails to reach completion. The same applies to the mixture of the male and the female : they require the right proportional relationship, and that is the reason why it happens that many couples fail to effect generation with one another, but if they change partners they succeed ; and also that these oppositions occur sometimes in young people, sometimes among those who are older, both with regard to failure and success in generation and also with regard to the generation of male and female offspring. (c) Also, one country differs from another in these respects, and one water from another, on account of the same causes, for the quality of the nourishment especially and of the bodily condition of a person


depends upon the blend (a) of the surrounding air and of the foods which the body takes up, and especially upon the nourishment supplied by the water, since this is what we take most of, water being present as nourishment in everything, even in solid substances as well. Hence hard, cold water in some cases causes barrenness, in others the birth of females.(b)

The following things are due to these same causes. Some offspring take after their parents and some do not; some after their father, some after their mother, as well in respect of the body as a whole as in respect of each of the parts, and they take after their parents more than after their earlier ancestors, and after their ancestors more than after any casual persons. Males take after their father more than their mother, females after their mother. Some take after none of their kindred, although they take after some human being at any rate ; others do not take after a human being at all in their appearance, but have gone so far that they resemble a monstrosity, and, for the matter of that, anyone who does not take after his parents is really in a way a monstrosity, since in these cases Nature has in a way strayed from the generic type. The first beginning of this deviation is when a female is formed instead of a male, though (a) this indeed is a necessity required by Nature,(c) since the race of creatures which are separated into male and female has got to be kept in being (d); and (b) since it is possible for the male sometimes not to gain the mastery either on account of youth or age or some other such cause, female

produced in the normal course of nature

ωσπερ `αναπηρίαν φνσικήν). See Introd. § 13.

(d) This is an instance of a necessity required by the Final Cause ; see 731 b 25—732 a 3.


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