on examining the question, however, the opposite appears more likely, for it is not hard to refute the above arguments and the view involves impossibilities. first, then, the resemblance of children to parents is no proof that the semen comes from the whole body, because the resemblance is found also in voice, nails, hair, and way of moving, from which nothing comes. and men generate before they yet have certain characters, such as a beard or grey hair. further, children are like their more remote ancestors from whom nothing has come, for the resemblances recur at an interval of many generations, as in the case of the woman in elis who had intercourse with the aethiop; her daughter was not an aethiop but the son of that daughter was. the same thing applies also to plants, for it is clear that if this theory were true the seed would come from all parts of plants also; but often a plant does not possess one part, and another part may be removed, and a third grows afterwards. besides, the seed does not come from the pericarp, and yet this also comes into being with the same form as in the parent plant.

we may also ask whether the semen comes from each of the homogeneous parts only, such as flesh and bone and sinew, or also from the heterogeneous, such as face and hands. for if from the former only, we object that resemblance exists rather in the heterogeneous parts, such as face and hands and feet; if then it is not because of the semen coming from all parts that children resemble their parents in these, what is there to stop the homogeneous parts also from being like for some other reason than this? if the semen comes from the heterogeneous alone, then it does not come from all parts; but it is more fitting that it should come from the homogeneous parts, for they are prior to the heterogeneous which are composed of them; and as children are born like their parents in face and hands, so they are, necessarily, in flesh and nails. if the semen comes from both, what would be the manner of generation? for the heteroeneous parts are composed of the homogneous, so that to come from the former would be to come from the latter and from their composition. to make this clearer by an illustration, take a written name; if anything came from the whole of it, it would be from each of the syllables, and if from these, from the letters and their composition. so that if really flesh and bones are composed of fire and the like elements, the semen would come rather from the elements than anything else, for how can it come from their composition? yet without this composition there would be no resemblance. if again something creates this composition later, it would be this that would be the cause of the resemblance, not the coming of the semen from every part of the body.

further, if the parts of the future animal are separated in the semen, how do they live? and if they are connected, they would form a small animal.

and what about the generative parts? for that which comes from the male is not similar to what comes from the female.

again, if the semen comes from all parts of both parents alike, the result is two animals, for the offspring will have all the parts of both. wherefore empedocles seems to say what agrees pretty well with this view (if we are to adopt it), to a certain extent at any rate, but to be wrong if we think otherwise. what he says agrees with it when he declares that there is a sort of tally in the male and female, and that the whole offspring does not come from either, ‘but sundered is the fashion of limbs, some in man’s . . . ’ for why does not the female generate from herself if the semen comes from all parts alike and she has a receptacle ready in the uterus? but, it seems, either it does not come from all the parts, or if it does it is in the way empedocles says, not the same parts coming from each parent, which is why they need intercourse with each other.

yet this also is impossible, just as much as it is impossible for the parts when full grown to survive and have life in them when torn apart, as empedocles accounts for the creation of animals; in the time of his ‘reign of love’, says he, ‘many heads sprang up without necks,’ and later on these isolated parts combined into animals. now that this is impossible is plain, for neither would the separate parts be able to survive without having any soul or life in them, nor if they were living things, so to say, could several of them combine so as to become one animal again. yet those who say that semen comes from the whole of the body really have to talk in that way, and as it happened then in the earth during the ‘reign of love’, so it happens according to them in the body. now it is impossible that the parts should be united together when they come into being and should come from different parts of the parent, meeting together in one place. then how can the upper and lower, right and left, front and back parts have been ‘sundered’? all these points are unintelligible. further, some parts are distinguished by possessing a faculty, others by being in certain states or conditions; the heterogeneous, as tongue and hand, by the faculty of doing something, the homogeneous by hardness and softness and the other similar states. blood, then, will not be blood, nor flesh flesh, in any and every state. it is clear, then, that that which comes from any part, as blood from blood or flesh from flesh, will not be identical with that part. but if it is something different from which the blood of the offspring comes, the coming of the semen from all the parts will not be the cause of the resemblance, as is held by the supporters of this theory. for if blood is formed from something which is not blood, it is enough that the semen come from one part only, for why should not all the other parts of the offspring as well as blood be formed from one part of the parent? indeed, this theory seems to be the same as that of anaxagoras, that none of the homogeneous parts come into being, except that these theorists assume, in the case of the generation of animals, what he assumed of the universe.

then, again, how will these parts that came from all the body of the parent be increased or grow? it is true that anaxagoras plausibly says that particles of flesh out of the food are added to the flesh. but if we do not say this (while saying that semen comes from all parts of the body), how will the foetus become greater by the addition of something else if that which is added remain unchanged? but if that which is added can change, then why not say that the semen from the very first is of such a kind that blood and flesh can be made out of it, instead of saying that it itself is blood and flesh? nor is there any other alternative, for surely we cannot say that it is increased later by a process of mixing, as wine when water is poured into it. for in that case each element of the mixture would be itself at first while still unmixed, but the fact rather is that flesh and bone and each of the other parts is such later. and to say that some part of the semen is sinew and bone is quite above us, as the saying is.

besides all this there is a difficulty if the sex is determined in conception (as empedocles says: ‘it is shed in clean vessels; some wax female, if they fall in with cold’). anyhow, it is plain that both men and women change not only from infertile to fertile, but also from bearing female to bearing male offspring, which looks as if the cause does not lie in the semen coming from all the parent or not, but in the mutual proportion or disproportion of that comes from the woman and the man, or in something of this kind. it is clear, then, if we are to put this down as being so, that the female sex is not determined by the semen coming from any particular part, and consequently neither is the special sexual part so determined (if really the same semen can become either male or female child, which shows that the sexual part does not exist in the semen). why, then, should we assert this of this part any more than of others? for if semen does not come from this part, the uterus, the same account may be given of the others.

again, some creatures come into being neither from parents of the same kind nor from parents of a different kind, as flies and the various kinds of what are called fleas; from these are produced animals indeed, but not in this case of similar nature but a kind of scolex. it is plain in this case that the young of a different kind are not produced by semen coming from all parts of the parent, for they would then resemble them, if indeed resemblance is a sign of its coming from all parts.

further even among animals some produce many young from a single coition (and something like this is universal among plants, for it is plain that they bear all the fruit of a whole season from a single movement). and yet how would this be possible if the semen were secreted from all the body? for from a single coition and a single segregation of the semen scattered throughout the body must needs follow only a single secretion. nor is it possible for it to be separated in the uterus, for this would no longer be a mere separation of semen, but, as it were, a severance from a new plant or animal.

again, the cuttings from a plant bear seed; clearly, therefore, even before they were cut from the parent plant, they bore their fruit from their own mass alone, and the seed did not come from all the plant.

but the greatest proof of all is derived from observations we have sufficiently established on insects. for, if not in all, at least in most of these, the female in the act of copulation inserts a part of herself into the male. this, as we said before, is the way they copulate, for the females manifestly insert this from below into the males above, not in all cases, but in most of those observed. hence it seems clear that, when the males do emit semen, then also the cause of the generation is not its coming from all the body, but something else which must be investigated hereafter. for even if it were true that it comes from all the body, as they say, they ought not to claim that it comes from all parts of it, but only from the creative part — from the workman, so to say, not the material he works in. instead of that, they talk as if one were to say that the semen comes from the shoes, for, generally speaking, if a son is like his father, the shoes he wears are like his father’s shoes.

as to the vehemence of pleasure in sexual intercourse, it is not because the semen comes from all the body, but because there is a strong friction (wherefore if this intercourse is often repeated the pleasure is diminished in the persons concerned). moreover, the pleasure is at the end of the act, but it ought, on the theory, to be in each of the parts, and not at the same time, but sooner in some and later in others.

if mutilated young are born of mutilated parents, it is for the same reason as that for which they are like them. and the young of mutilated parents are not always mutilated, just as they are not always like their parents; the cause of this must be inquired into later, for this problem is the same as that.

again, if the female does not produce semen, it is reasonable to suppose it does not come from all the body of the male either. conversely, if it does not come from all the male it is not unreasonable to suppose that it does not come from the female, but that the female is cause of the generation in some other way. into this we must next inquire, since it is plain that the semen is not secreted from all the parts.

in this investigation and those which follow from it, the first thing to do is to understand what semen is, for then it will be easier to inquire into its operations and the phenomena connected with it. now the object of semen is to be of such a nature that from it as their origin come into being those things which are naturally formed, not because there is any agent which makes them from it as simply because this is the semen. now we speak of one thing coming from another in many senses; it is one thing when we say that night comes from day or a man becomes man from boy, meaning that a follows b; it is another if we say that a statue is made from bronze and a bed from wood, and so on in all the other cases where we say that the thing made is made from a material, meaning that the whole is formed from something preexisting which is only put into shape. in a third sense a man becomes unmusical from being musical, sick from being well, and generally in this sense contraries arise from contraries. fourthly, as in the ‘climax’ of epicharmus; thus from slander comes railing and from this fighting, and all these are from something in the sense that it is the efficient cause. in this last class sometimes the efficient cause is in the things themselves, as in the last mentioned (for the slander is a part of the whole trouble), and sometimes external, as the art is external to the work of art or the torch to the burning house. now the offspring comes from the semen, and it is plainly in one of the two following senses that it does so — either the semen is the material from which it is made, or it is the first efficient cause. for assuredly it is not in the sense of a being after b, as the voyage comes from, i.e. after, the panathenaea; nor yet as contraries come from contraries, for then one of the two contraries ceases to be, and a third substance must exist as an immediate underlying basis from which the new thing comes into being. we must discover then, in which of the two other classes the semen is to be put, whether it is to be regarded as matter, and therefore acted upon by something else, or as a form, and therefore acting upon something else, or as both at once. for perhaps at the same time we shall see clearly also how all the products of semen come into being from contraries, since coming into being from contraries is also a natural process, for some animals do so, i.e. from male and female, others from only one parent, as is the case with plants and all those animals in which male and female are not separately differentiated. now that which comes from the generating parent is called the seminal fluid, being that which first has in it a principle of generation, in the case of all animals whose nature it is to unite; semen is that which has in it the principles from both united parents, as the first mixture which arises from the union of male and female, be it a foetus or an ovum, for these already have in them that which comes from both. (semen, or seed, and grain differ only in the one being earlier and the other later, grain in that it comes from something else, i.e. the seed, and seed in that something else, the grain, comes from it, for both are really the same thing.)

we must again take up the question what the primary nature of what is called semen is. needs must everything which we find in the body either be (1) one of the natural parts, whether homogeneous or heterogeneous, or (2) an unnatural part such as a growth, or (3) a secretion or excretion, or (4) waste-product, or (5) nutriment. (by secretion or excretion i mean the residue of the nutriment, by waste-product that which is given off from the tissues by an unnatural decomposition.)

now that semen cannot be a part of the body is plain, for it is homogeneous, and from the homogeneous nothing is composed, e.g. from only sinew or only flesh; nor is it separated as are all the other parts. but neither is it contrary to nature nor a defect, for it exists in all alike, and the development of the young animal comes from it. nutriment, again, is obviously introduced from without.

it remains, then, that it must be either a waste-product or a secretion or excretion. now the ancients seem to think that it is a waste-product, for when they say that it comes from all the body by reason of the heat of the movement of the body in copulation, they imply that it is a kind of waste-product. but these are contrary to nature, and from such arises nothing according to nature. so then it must be a secretion or excretion.

but, to go further into it, every secretion or excretion is either of useless or useful nutriment; by ‘useless’ i mean that from which nothing further is contributed to natural growth, but which is particularly mischievous to the body if too much of it is consumed; by ‘useful’ i mean the opposite. now it is evident that it cannot be of the former character, for such is most abundant in persons of the worst condition of body through age or sickness; semen, on the contrary, is least abundant in them for either they have none at all or it is not fertile, because a useless and morbid secretion is mingled with it.

semen, then, is part of a useful secretion. but the most useful is the last and that from which finally is formed each of the parts of the body. for secretions are either earlier or later; of the nutriment in the first stage the secretion is phlegm and the like, for phlegm also is a secretion of the useful nutriment, an indication of this being that if it is mixed with pure nutriment it is nourishing, and that it is used up in cases of illness. the final secretion is the smallest in proportion to the quantity of nutriment. but we must reflect that the daily nutriment by which animals and plants grow is but small, for if a very little be added continually to the same thing the size of it will become excessive.

so we must say the opposite of what the ancients said. for whereas they said that semen is that which comes from all the body, we shall say it is that whose nature is to go to all of it, and what they thought a waste-product seems rather to be a secretion. for it is more reasonable to suppose that the last extract of the nutriment which goes to all parts resembles that which is left over from it, just as part of a painter’s colour is often left over resembling that which he has used up. waste-products, on the contrary, are always due to corruption or decay and to a departure from nature.

a further proof that it is not a waste-product, but rather a secretion, is the fact that the large animals have few young, the small many. for the large must have more waste and less secretion, since the great size of the body causes most of the nutriment to be used up, so that the residue or secretion is small.

again, no place has been set apart by nature for waste-products but they flow wherever they can find an easy passage in the body, but a place has been set apart for all the natural secretions; thus the lower intestine serves for the excretion of the solid nutriment, the bladder for that of the liquid; for the useful part of the nutriment we have the upper intestine, for the spermatic secretions the uterus and pudenda and breasts, for it is collected and flows together into them.

and the resulting phenomena are evidence that semen is what we have said, and these result because such is the nature of the secretion. for the exhaustion consequent on the loss of even a very little of the semen is conspicuous because the body is deprived of the ultimate gain drawn from the nutriment. with some few persons, it is true, during a short time in the flower of their youth the loss of it, if it be excessive in quantity, is an alleviation (just as in the case of the nutriment in its first stage, if too much have been taken, since getting rid of this also makes the body more comfortable), and so it may be also when other secretions come away with it, for in that case it is not only semen that is lost but also other influences come away mingled with it, and these are morbid. wherefore, with some men at least, that which comes from them proves sometimes incapable of procreation because the seminal element in it is so small. but still in most men and as a general rule the result of intercourse is exhaustion and weakness rather than relief, for the reason given. moreover, semen does not exist in them either in childhood or in old age or in sickness — in the last case because of weakness, in old age because they do not sufficiently concoct their food, and in childhood because they are growing and so all the nutriment is used up too soon, for in about five years, in the case of human beings at any rate, the body seems to gain half the height that is gained in all the rest of life.

in many animals and plants we find a difference in this connexion not only between kinds as compared with kinds, but also between similar individuals of the same kind as compared with each other, e.g. man with man or vine with vine. some have much semen, others little, others again none at all, not through weakness but the contrary, at any rate in some cases. this is because the nutriment is used up to form the body, as with some human beings, who, being in good condition and developing much flesh or getting rather too fat, produce less semen and are less desirous of intercourse. like this is what happens with those vines which ‘play the goat’, that is, luxuriate wantonly through too much nutrition, for he-goats when fat are less inclined to mount the female; for which reason they thin them before breeding from them, and say that the vines ‘play the goat’, so calling it from the condition of the goats. and fat people, women as well as men, appear to be less fertile than others from the fact that the secretion when in process of concoction turns to fat with those who are too well-nourished. for fat also is a healthy secretion due to good living.

in some cases no semen is produced at all, as by the willow and poplar. this condition is due to each of the two causes, weakness and strength; the former prevents concoction of the nutriment, the latter causes it to be all consumed, as said above. in like manner other animals produce much semen through weakness as well as through strength, when a great quantity of a useless secretion is mixed with it; this sometimes results in actual disease when a passage is not found to carry off the impurity, and though some recover of this, others actually die of it. for corrupt humours collect here as in the urine, which also has been known to cause disease.

[further the same passage serves for urine and semen; and whatever animals have both kinds of excrement, that of liquid and that of solid nutriment, discharge the semen by the same passage as the liquid excrement (for it is a secretion of a liquid, since the nutriment of all animals is rather liquid than solid), but those which have no liquid excrement discharge it at the passage of the solid residua. moreover, waste-products are always morbid, but the removal of the secretion is useful; now the discharge of the semen participates in both characteristics because it takes up some of the non-useful nutriment. but if it were a waste-product it would be always harmful; as it is, it is not so.]

from what has been said, it is clear that semen is a secretion of useful nutriment, and that in its last stage, whether it is produced by all or no.