Book One

. Since feeling and voluntary motion are peculiar to animals, whilstgrowth and nutrition are common to plants as well, we may look onthe former as effects of the soul and the latter as effects of thenature. And if there be anyone who allows a share in soul to plantsas well, and separates the two kinds of soul, naming the kind in questionvegetative, and the other sensory, this person is not saying anythingelse, although his language is somewhat unusual. We, however, forour part, are convinced that the chief merit of language is clearness,and we know that nothing detracts so much from this as do unfamiliarterms; accordingly we employ those terms which the bulk of peopleare accustomed to use, and we say that animals are governed at onceby their soul and by their nature, and plants by their nature alone,and that growth and nutrition are the effects of nature, not of soul.

. Thus we shall enquire, in the course of this treatise, from whatfaculties these effects themselves, as well as any other effects ofnature which there may be, take their origin. 

First, however, we must distinguish and explain clearly the variousterms which we are going to use in this treatise, and to what thingswe apply them; and this will prove to be not merely an explanationof terms but at the same time a demonstration of the effects of nature.

When, therefore, such and such a body undergoes no change from itsexisting state, we say that it is at rest; but, not withstanding,if it departs from this in any respect we then say that in this respectit undergoes motion. Accordingly, when it departs in various waysfrom its preexisting state, it will be said to undergo various kindsof motion. Thus, if that which is white becomes black, or what isblack becomes white, it undergoes motion in respect to colour; orif what was previously sweet now becomes bitter, or, conversely, frombeing bitter now becomes sweet, it will be said to undergo motionin respect to flavour; to both of these instances, as well as to thosepreviously mentioned, we shall apply the term qualitative motion.And further, it is not only things which are altered in regard tocolour and flavour which, we say, undergo motion; when a warm thingbecomes cold, and a cold warm, here too we speak of its undergoingmotion; similarly also when anything moist becomes dry, or dry moist.Now, the common term which we apply to all these cases is alteration.

This is one kind of motion. But there is another kind which occursin bodies which change their position, or as we say, pass from oneplace to another; the name of this is transference. 

These two kinds of motion, then, are simple and primary, while compoundedfrom them we have growth and decay, as when a small thing becomesbigger, or a big thing smaller, each retaining at the same time itsparticular form. And two other kinds of motion are genesis and destruction,genesis being a coming into existence, and destruction being the opposite.

Now, common to all kinds of motion is change from the preexistingstate, while common to all conditions of rest is retention of thepreexisting state. The Sophists, however, while allowing that breadin turning into blood becomes changed as regards sight, taste, and touch, will not agree that this change occurs in reality. Thus someof them hold that all such phenomena are tricks and illusions of oursenses; the senses, they say, are affected now in one way, now inanother, whereas the underlying substance does not admit of any ofthese changes to which the names are given. Others (such as Anaxagoras)will have it that the qualities do exist in it, but that they areunchangeable and immutable from eternity to eternity, and that theseapparent alterations are brought about by separation and combination.

Now, if I were to go out of my way to confute these people, my subsidiarytask would be greater than my main one. Thus, if they do not knowall that has been written, "On Complete Alteration of Substance" byAristotle, and after him by Chrysippus, I must beg of them to makethemselves familiar with these men's writings. If, however, they knowthese, and yet willingly prefer the worse views to the better, theywill doubtless consider my arguments foolish also. I have shown elsewherethat these opinions were shared by Hippocrates, who lived much earlierthan Aristotle. In fact, all those known to us who have been bothphysicians and philosophers Hippocrates was the first who took inhand to demonstrate that there are, in all, four mutually interactingqualities, and that to the operation of these is due the genesis and destruction of all things that come into and pass out of being. Nay,more; Hippocrates was also the first to recognise that all these qualitiesundergo an intimate mingling with one another; and at least the beginningsof the proofs to which Aristotle later set his hand are to be foundfirst in the writings of Hippocrates. 

As to whether we are to suppose that the substances as well as theirqualities undergo this intimate mingling, as Zeno of Citium afterwardsdeclared, I do not think it necessary to go further into this questionin the present treatise; for immediate purposes we only need to recognizethe complete alteration of substance. In this way, nobody will supposethat bread represents a kind of meeting-place for bone, flesh, nerve,and all the other parts, and that each of these subsequently becomesseparated in the body and goes to join its own kind; before any separationtakes place, the whole of the bread obviously becomes blood; (at anyrate, if a man takes no other food for a prolonged period, he willhave blood enclosed in his veins all the same). And clearly this disprovesthe view of those who consider the elements unchangeable, as also,for that matter, does the oil which is entirely used up in the flameof the lamp, or the faggots which, in a somewhat longer time, turninto fire. 

I said, however, that I was not going to enter into an argument withthese people, and it was only because the example was drawn from thesubject-matter of medicine, and because I need it for the presenttreatise, that I have mentioned it. We shall then, as I said, renounceour controversy with them, since those who wish may get a good graspof the views of the ancients from our own personal investigationsinto these matters. 

The discussion which follows we shall devote entirely, as we originallyproposed, to an enquiry into the number and character of the facultiesof Nature, and what is the effect which each naturally produces. Now,of course, I mean by an effect that which has already come into existence and has been completed by the activity of these faculties - for example,blood, flesh, or nerve. And activity is the name I give to the activechange or motion, and the cause of this I call a faculty. Thus, whenfood turns into blood, the motion of the food is passive, and thatof the vein active. Similarly, when the limbs have their positiontheir position altered, it is the muscle which produces, and the boneswhich undergo the motion. In these cases I call the motion of thevein and of the muscle an activity, and that of the food and the bonesa symptom or affection, since the first group undergoes alteration and the second group is merely transported. One might, therefore,also speak of the activity as an effect of Nature - for example, digestion,absorption, blood-production; one could not, however, in every casecall the effect an activity; thus flesh is an effect of Nature, butit is, of course, not an activity. It is, therefore, clear that oneof these terms is used in two senses, but not the other.

. It appears to me, then, that the vein, as well as each of the otherparts, functions in such and such a way according to the manner inwhich the four qualities are mixed. There are, however, a considerablenumber of not undistinguished men - philosophers and physicians - whorefer action to the Warm and the Cold, and who subordinate to these,as passive, the Dry and the Moist; Aristotle, in fact, was the firstwho attempted to bring back the causes of the various special activitiesto these principles, and he was followed later by the Stoic school.These latter, of course, could logically make active principles ofthe Warm and Cold, since they refer the change of the elements themselvesinto one another to certain diffusions and condensations. This doesnot hold of Aristotle, however; seeing that he employed the four qualitiesto explain the genesis of the elements, he ought properly to havealso referred the causes of all the special activities to these. Howis it that he uses the four qualities in his book "On Genesis and Destruction," whilst in his "Meteorology," his "Problems," and manyother works he uses the uses the two only? Of course, if anyone wereto maintain that in the case of animals and plants the Warm and Coldare more active, the Dry and Moist less so, he might perhaps haveeven Hippocrates on his side; but if he were to say that this happensin all cases, he would, I imagine, lack support, not merely from Hippocrates,but even from Aristotle himself - if, at least, Aristotle chose toremember what he himself taught us in his work "On Genesis and Destruction,"not as a matter of simple statement, but with an accompanying demonstration.I have, however, also investigated these questions, in so far as theyare of value to a physician, in my work "On Temperaments."

. The so-called blood-making faculty in the veins, then, as wellas all the other faculties, fall within the category of relative concepts;primarily because the faculty is the cause of the activity, but also,accidentally, because it is the cause of the effect. But, if the causeis relative to something - for it is the cause of what results fromit, and of nothing else - it is obvious that the faculty also fallsinto the category of the relative; and so long as we are ignorantof the true essence of the cause which is operating, we call it afaculty. Thus we say that there exists in the veins a blood-makingfaculty, as also a digestive faculty in the stomach, a pulsatile facultyin the heart, and in each of the other parts a special faculty correspondingto the function or activity of that part. If, therefore, we are toinvestigate methodically the number and kinds of faculties, we mustbegin with the effects; for each of these effects comes from a certainactivity, and each of these again is preceded by a cause.

. The effects of Nature, then, while the animal is still being formedin the womb, are all the different parts of its body; and after ithas been born, an effect in which all parts share is the progressof each to its full size, and thereafter its maintenance of itselfas long as possible. 

The activities corresponding to the three effects mentioned are necessarily three - one to each - namely, Genesis, Growth, and Nutrition. Genesis,however, is not a simple activity of Nature, but is compounded ofalteration and of shaping. That is to say, in order that bone, nerve,veins, and all other [tissues] may come into existence, the underlyingsubstance from which the animal springs must be altered; and in orderthat the substance so altered may acquire its appropriate shape and position, its cavities, outgrowths, attachments, and so forth, ithas to undergo a shaping or formative process. One would be justifiedin calling this substance which undergoes alteration the materialof the animal, just as wood is the material of a ship, and wax ofan image. 

Growth is an increase and expansion in length, breadth, and thicknessof the solid parts of the animal (those which have been subjectedto the moulding or shaping process). Nutrition is an addition to these,without expansion. 

. Let us speak then, in the first place, of Genesis, which, as wehave said, results from alteration together with shaping.

The seed having been cast into the womb or into the earth (for thereis no difference), then, after a certain definite period, a greatnumber of parts become constituted in the substance which is beinggenerated; these differ as regards moisture, dryness, coldness and warmth, and in all the other qualities which naturally derive therefrom.These derivative qualities, you are acquainted with, if you have givenany sort of scientific consideration to the question of genesis and destruction. For, first and foremost after the qualities mentionedcome the other so-called tangible distinctions, and after them thosewhich appeal to taste, smell, and sight. Now, tangible distinctionsare hardness and softness, viscosity, friability, lightness, heaviness,density, rarity, smoothness, roughness, thickness and thinness; allof these have been duly mentioned by Aristotle. And of course youknow those which appeal to taste, smell, and sight. Therefore, ifyou wish to know which alterative faculties are primary and elementary,they are moisture, dryness, coldness, and warmth, and if you wishto know which ones arise from the combination of these, they willbe found to be in each animal of a number corresponding to its sensibleelements. The name sensible elements is given to all the homogeneousparts of the body, and these are to be detected not by any system,but by personal observation of dissections. 

Now Nature constructs bone, cartilage, nerve, membrane, ligament,vein, and so forth, at the first stage of the animal's genesis, employingat this task a faculty which is, in general terms, generative and alterative, and, in more detail, warming, chilling, drying, or moistening;or such as spring from the blending of these, for example, the bone-producing, nerve-producing, and cartilage-producing faculties (since for thesake of clearness these names must be used as well). 

Now the peculiar flesh of the liver is of this kind as well, alsothat of the spleen, that of the kidneys, that of the lungs, and thatof the heart; so also the proper substance of the brain, stomach,gullet, intestines, and uterus is a sensible element, of similar partsall through, simple, and uncompounded. That is to say, if you removefrom each of the organs mentioned its arteries, veins, and nerves,the substance remaining in each organ is, from the point of view ofthe senses, simple and elementary. As regards those organs consistingof two dissimilar coats, of which each is simple, of these organsthe coats are the are the elements - for example, the coats of thestomach, oesophagus, intestines, and arteries; each of these two coatshas an alterative faculty peculiar to it, which has engendered itfrom the menstrual blood of the mother. Thus the special alterativefaculties in each animal are of the same number as the elementaryparts; and further, the activities must necessarily correspond eachto one of the special parts, just as each part has its special use - for example, those ducts which extend from the kidneys into the bladder,and which are called ureters; for these are not arteries, since theydo not pulsate nor do they consist of two coats; and they are notveins, since they neither contain blood, nor do their coats in anyway resemble those of veins; from nerves they differ still more thanfrom the structures mentioned. 

"What, then, are they?" someone asks - as though every part must necessarilybe either an artery, a vein, a nerve, or a complex of these, and asthough the truth were not what I am now stating, namely, that everyone of the various organs has its own particular substance. For infact the two bladders - that which receives the urine, and that whichreceives the yellow bile - not only differ from all other organs, butalso from one another. Further, the ducts which spring out like kindsof conduits from the gall-bladder and which pass into the liver haveno resemblance either to arteries, veins or nerves. But these partshave been treated at a greater length in my work "On the Anatomy ofHippocrates," as well as elsewhere. 

As for the actual substance of the coats of the stomach, intestine,and uterus, each of these has been rendered what it is by a specialalterative faculty of Nature; while the bringing of these together,the therewith of the structures which are inserted into them, theoutgrowth into the intestine, the shape of the inner cavities, and the like, have all been determined by a faculty which we call theshaping or formative faculty; this faculty we also state to be artistic-nay, the best and highest art - doing everything for some purpose,so that there is nothing ineffective or superfluous, or capable ofbeing better disposed. This, however, I shall demonstrate in my work"On the Use of Parts." 

. Passing now to the faculty of Growth let us first mention thatthis, too, is present in the foetus in utero as is also the nutritivefaculty, but that at that stage these two faculties are, as it were,handmaids to those already mentioned, and do not possess in themselvessupreme authority. When, however, the animal has attained its completesize, then, during the whole period following its birth and untilthe acme is reached, the faculty of growth is predominant, while thealterative and nutritive faculties are accessory - in fact, act asits handmaids. What, then, is the property of this faculty of growth?To extend in every direction that which has already come into existence - that is to say, the solid parts of the body, the arteries, veins,nerves, bones, cartilages, membranes, ligaments, and the various coatswhich we have just called elementary, homogeneous, and simple. And I shall state in what way they gain this extension in every direction,first giving an illustration for the sake of clearness. 

Children take the bladders of pigs, fill them with air, and then rubthem on ashes near the fire, so as to warm, but not to injure them.This is a common game in the district of Ionia, and among not a fewother nations. As they rub, they sing songs, to a certain measure,time, and rhythm, and all their words are an exhortation to the bladderto increase in size. When it appears to them fairly well distended,they again blow air into it and expand it further; then they rub itagain. This they do several times, until the bladder seems to themto have become large enough. Now, clearly, in these doings of thechildren, the more the interior cavity of the bladder increases insize, the thinner, necessarily, does its substance become. But, ifthe children were able to bring nourishment to this thin part, thenthey would make the bladder big in the same way that Nature does.As it is, however, they cannot do what Nature does, for to imitatethis is beyond the power not only of children, but of any one soever;it is a property of Nature alone. 

It will now, therefore, be clear to you that nutrition is a necessityfor growing things. For if such bodies were distended, but not atthe same time nourished, they would take on a false appearance ofgrowth, not a true growth. And further, to be distended in all directionsbelongs only to bodies whose growth is directed by Nature; for thosewhich are distended by us undergo this distension in one directionbut grow less in the others; it is impossible to find a body whichwill remain entire and not be torn through whilst we stretch it inthe three dimensions. Thus Nature alone has the power to expand abody in all directions so that it remains unruptured and preservescompletely its previous form. 

Such then is growth, and it cannot occur without the nutriment whichflows to the part and is worked up into it. 

. We have, then, it seems, arrived at the subject of Nutrition, whichis the third and remaining consideration which we proposed at theoutset. For, when the matter which flows to each part of the bodyin the form of nutriment is being worked up into it, this activityis nutrition, and its cause is the nutritive faculty. Of course, thekind of activity here involved is also an alteration, but not an alterationlike that occurring at the stage of genesis. For in the latter casesomething comes into existence which did not exist previously, whilein nutrition the inflowing material becomes assimilated to that whichhas already come into existence. Therefore, the former kind of alterationhas with reason been termed genesis, and the latter, assimilation.

. Now, since the three faculties of Nature have been exhaustivelydealt with, and the animal would appear not to need any others (beingpossessed of the means for growing, for attaining completion, and for maintaining itself as long a time as possible), this treatisemight seem to be already complete, and to constitute an expositionof all the faculties of Nature. If, however, one considers that ithas not yet touched upon any of the parts of the animal (I mean thestomach, intestines, liver, and the like), and that it has not dealtwith the faculties resident in these, it will seem as though merelya kind of introduction had been given to the practical parts of ourteaching. For the whole matter is as follows: Genesis, growth, and nutrition are the first, and, so to say, the principal effects ofNature; similarly also the faculties which produce these effects - the first faculties - are three in number, and are the most dominatingof all. But as has already been shown, these need the service bothof each other, and of yet different faculties. Now, these which thefaculties of generation and growth require have been stated. I shallnow say what ones the nutritive faculty requires. 

. For I believe that I shall prove that the organs which have todo with the disposal of the nutriment, as also their faculties, existfor the sake of this nutritive faculty. For since the action of thisfaculty is assimilation, and it is impossible for anything to be assimilatedby, and to change into anything else unless they already possess acertain community and affinity in their qualities, therefore, in thefirst place, any animal cannot naturally derive nourishment from anykind of food, and secondly, even in the case of those from which itcan do so, it cannot do this at once. Therefore, by reason of thislaw, every animal needs several organs for altering the nutriment.For in order that the yellow may become red, and the red yellow, onesimple process of alteration is required, but in order that the whitemay become black, and the black white, all the intermediate stagesare needed. So also, a thing which is very soft cannot all at oncebecome very hard, nor vice versa; nor, similarly can anything whichhas a very bad smell suddenly become quite fragrant, nor again, canthe converse happen. 

How, then, could blood ever turn into bone, without having first become,as far as possible, thickened and white? And how could bread turninto blood without having gradually parted with its whiteness and gradually acquired redness? Thus it is quite easy for blood to becomeflesh; for, if Nature thicken it to such an extent that it acquiresa certain consistency and ceases to be fluid, it thus becomes originalnewly-formed flesh; but in order that blood may turn into bone, muchtime is needed and much elaboration and transformation of the blood.Further, it is quite clear that bread, and, more particularly lettuce,beet, and the like, require a great deal of alteration, in order tobecome blood. 

This, then, is one reason why there are so many organs concerned inthe alteration of food. A second reason is the nature of the superfluities.For, as we are unable to draw any nourishment from grass, althoughthis is possible for cattle, similarly we can derive nourishment fromradishes, albeit not to the same extent as from meat; for almost thewhole of the latter is mastered by our natures; it is transformed and altered and constituted useful blood; but, not withstanding, inthe radish, what is appropriate and capable of being altered (and that only with difficulty, and with much labour) is the very smallestpart; almost the whole of it is surplus matter, and passes throughthe digestive organs, only a very little being taken up into the veinsas blood - nor is this itself entirely utilisable blood. Nature, therefore,had need of a second process of separation for the superfluities inthe veins. Moreover, these superfluities need, on the one hand, certainfresh routes to conduct them to the outlets, so that they may notspoil the useful substances, and they also need certain reservoirs,as it were, in which they are collected till they reach a sufficientquantity, and are then discharged. 

Thus, then, you have discovered bodily parts of a second kind, consecratedin this case to the [removal of the] superfluities of the food. Thereis, however, also a third kind, for carrying the pabulum in everydirection; these are like a number of roads intersecting the wholebody. 

Thus there is one entrance - that through the mouth - for all the variousarticles of food. What receives nourishment, however, is not one singlepart, but a great many parts, and these widely separated; do not besurprised, therefore, at the abundance of organs which Nature hascreated for the purpose of nutrition. For those of them which haveto do with alteration prepare the nutriment suitable for each part;others separate out the superfluities; some pass these along, othersstore them up, others excrete them; some, again, are paths for thetransit in all directions of the utilisable juices. So, if you wishto gain a thorough acquaintance with all the faculties of Nature,you will have consider each one of these organs. 

Now in giving an account of these we must begin with those effectsof Nature, together with their corresponding parts and faculties,which are closely connected with the purpose to be achieved.

. Let us once more, then, recall the actual purpose for which Naturehas constructed all these parts. Its name, as previously stated, isnutrition, and the definition corresponding to the name is: an assimilationof that which nourishes to that which receives nourishment. And inorder that this may come about, we must assume a preliminary processof adhesion, and for that, again, one of presentation. For wheneverthe juice which is destined to nourish any of the parts of the animalis emitted from the vessels, it is in the first place dispersed allthrough this part, next it is presented, and next it adheres, and becomes completely assimilated. 

The so-called white [leprosy] shows the difference between assimilation and adhesion, in the same way that the kind of dropsy which some peoplecall anasarca clearly distinguishes presentation from adhesion. For,of course, the genesis of such a dropsy does not come about as dosome of the conditions of atrophy and wasting, from an insufficientsupply of moisture; the flesh is obviously moist enough,- in factit is thoroughly saturated,- and each of the solid parts of the bodyis in a similar condition. While, however, the nutriment conveyedto the part does undergo presentation, it is still too watery, and is not properly transformed into a juice, nor has it acquired thatviscous and agglutinative quality which results from the operationof innate heat; therefore, adhesion cannot come about, since, owingto this abundance of thin, crude liquid, the pabulum runs off and easily slips away from the solid parts of the body. In white [leprosy],again, there is adhesion of the nutriment but no real assimilation.From this it is clear that what I have just said is correct, namely,that in that part which is to be nourished there must first occurpresentation, next adhesion, and finally assimilation proper.

Strictly speaking, then, nutriment is that which is actually nourishing,while the quasi-nutriment which is not yet nourishing (e.g. matterwhich is undergoing adhesion or presentation) is not, strictly speaking,nutriment, but is so called only by an equivocation. Also, that whichis still contained in the veins, and still more, that which is inthe stomach, from the fact that it is destined to nourish if properlyelaborated, has been called "nutriment." Similarly we call the variouskinds of food "nutriment," not because they are already nourishingthe animal, nor because they exist in the same state as the materialwhich actually is nourishing it, but because they are able and destinedto nourish it if they be properly elaborated. 

This was also what Hippocrates said, viz., "Nutriment is what is engagedin nourishing, as also is quasi-nutriment, and what is destined tobe nutriment." For to that which is already being assimilated he gavethe name of nutriment; to the similar material which is being presentedor becoming adherent, the name of quasi-nutriment; and to everythingelse - that is, contained in the stomach and veins - the name of destinednutriment. 

. It is quite clear, therefore, that nutrition must necessarilybe a process of assimilation of that which is nourishing to that whichis being nourished. Some, however, say that this assimilation doesnot occur in reality, but is merely apparent; these are the peoplewho think that Nature is not artistic, that she does not show forethoughtfor the animal's welfare, and that she has absolutely no native powerswhereby she alters some substances, attracts others, and dischargesothers. 

Now, speaking generally, there have arisen the following two sectsin medicine and philosophy among those who have made any definitepronouncement regarding Nature. I speak, of course, of such of themas know what they are talking about, and who realize the logical sequenceof their hypotheses, and stand by them; as for those who cannot understand even this, but who simply talk any nonsense that comes to their tongues,and who do not remain definitely attached either to one sect or theother - such people are not even worth mentioning. 

What, then, are these sects, and what are the logical consequencesof their hypotheses? The one class supposes that all substance whichis subject to genesis and destruction is at once continuous and susceptibleof alteration. The other school assumes substance to be unchangeable,unalterable, and subdivided into fine particles, which are separatedfrom one another by empty spaces. 

All people, therefore, who can appreciate the logical sequence ofan hypothesis hold that, according to the second teaching, there doesnot exist any substance or faculty peculiar either to Nature or toSoul, but that these result from the way in which the primary corpuscles,which are unaffected by change, come together. According to the first-mentioned teaching, on the other hand, Nature is not posterior to the corpuscles,but is a long way prior to them and older than they; and thereforein their view it is Nature which puts together the bodies both ofplants and animals; and this she does by virtue of certain facultieswhich she possesses - these being, on the one hand, attractive and assimilative of what is appropriate, and, on the other, of what isforeign. Further, she skilfully moulds everything during the stageof genesis; and she also provides for the creatures after birth, employinghere other faculties again, namely, one of affection and forethoughtfor offspring, and one of sociability and friendship for kindred.According to the other school, none of these things exist in the natures[of living things], nor is there in the soul any original innate idea,whether of agreement or difference, of separation or synthesis, ofjustice or injustice, of the beautiful or ugly; all such things, theysay, arise in us from sensation and through sensation, and animalsare steered by certain images and memories. 

Some of these people have even expressly declared that the soul possessesno reasoning faculty, but that we are led like cattle by the impressionof our senses, and are unable to refuse or dissent from anything.In their view, obviously, courage, wisdom, temperance, and self-control are all mere nonsense, we do not love either each other or our offspring,nor do the gods care anything for us. This school also despises dreams,birds, omens, and the whole of astrology, subjects with which we havedealt at greater length in another work, in which we discuss the viewsof Asclepiades the physician. Those who wish to do so may familiarizethemselves with these arguments, and they may also consider at thispoint which of the two roads lying before us is the better one totake. Hippocrates took the first-mentioned. According to this teaching,substance is one and is subject to alteration; there is a consensusin the movements of air and fluid throughout the whole body; Natureacts throughout in an artistic and equitable manner, having certainfaculties, by virtue of which each part of the body draws to itselfthe juice which is proper to it, and, having done so, attaches itto every portion of itself, and completely assimilates it; while suchpart of the juice as has not been mastered, and is not capable ofundergoing complete alteration and being assimilated to the part whichis being nourished, is got rid of by yet another (an expulsive) faculty.

. Now the extent of exactitude and truth in the doctrines of Hippocratesmay be gauged, not merely from the way in which his opponents areat variance with obvious facts, but also from the various subjectsof natural research themselves - the functions of animals, and therest. For those people who do not believe that there exists in anypart of the animal a faculty for attracting its own special qualityare compelled repeatedly to deny obvious facts. For instance, Asclepiades,the physician, did this in the case of the kidneys. That these areorgans for secreting [separating out] the urine, was the belief notonly of Hippocrates, Diocles, Erasistratus, Praxagoras, and all otherphysicians of eminence, but practically every butcher is aware ofthis, from the fact that he daily observes both the position of thekidneys and the duct (termed the ureter) which runs from each kidneyinto the bladder, and from this arrangement he infers their characteristicuse and faculty. But, even leaving the butchers aside, all peoplewho suffer either from frequent dysuria or from retention of urinecall themselves "nephritics," when they feel pain in the loins and pass sandy matter in their water. 

I do not suppose that Asclepiades ever saw a stone which had beenpassed by one of these sufferers, or observed that this was precededby a sharp pain in the region between kidneys and bladder as the stonetraversed the ureter, or that, when the stone was passed, both thepain and the retention at once ceased. It is worth while, then, learninghow his theory accounts for the presence of urine in the bladder,and one is forced to marvel at the ingenuity of a man who puts aside these broad, clearly visible routes, and postulates others which are narrow, invisible - indeed, entirely imperceptible. His view, in fact,is that the fluid which we drink passes into the bladder by being resolved into vapours, and that, when these have been again condensed,it thus regains its previous form, and turns from vapour into fluid.He simply looks upon the bladder as a sponge or a piece of wool, and not as the perfectly compact and impervious body that it is, withtwo very strong coats. For if we say that the vapours pass throughthese coats, why should they not pass through the peritoneum and thediaphragm, thus filling the whole abdominal cavity and thorax withwater? "But," says he, "of course the peritoneal coat is more imperviousthan the bladder, and this is why it keeps out the vapours, whilethe bladder admits them." Yet if he had ever practised anatomy, hemight have known that the outer coat of the bladder springs from the peritoneum and is essentially the same as it, and that the inner coat,which is peculiar to the bladder, is more than twice as thick as theformer. 

Perhaps, however, it is not the thickness or thinness of the coats,but the situation of the bladder, which is the reason for the vapoursbeing carried into it? On the contrary, even if it were probable forevery other reason that the vapours accumulate there, yet the situationof the bladder would be enough in itself to prevent this. For thebladder is situated below, whereas vapours have a natural tendencyto rise upwards; thus they would fill all the region of the thorax and lungs long before they came to the bladder. 

But why do I mention the situation of the bladder, peritoneum, and thorax? For surely, when the vapours have passed through the coatsof the stomach and intestines, it is in the space between these and the peritoneum that they will collect and become liquefied (just asin dropsical subjects it is in this region that most of the watergathers). Otherwise the vapours must necessarily pass straight forwardthrough everything which in any way comes in contact with them, and will never come to a standstill. But, if this be assumed, then theywill traverse not merely the peritoneum but also the epigastrium,and will become dispersed into the surrounding air; otherwise theywill certainly collect under the skin. 

Even these considerations, however, our present-day Asclepiadeansattempt to answer, despite the fact that they always get soundly laughedat by all who happen to be present at their disputations on thesesubjects - so difficult an evil to get rid of is this sectarian partizanship,so excessively resistant to all cleansing processes, harder to healthan any itch! 

Thus, one of our Sophists who is a thoroughly hardened disputer and as skilful a master of language as there ever was, once got into adiscussion with me on this subject; so far from being put out of countenanceby any of the above-mentioned considerations, he even expressed hissurprise that I should try to overturn obvious facts by ridiculousarguments! "For," said he, "one may clearly observe any day in thecase of any bladder, that, if one fills it with water or air and thenties up its neck and squeezes it all round, it does not let anythingout at any point, but accurately retains all its contents. And surely,"said he, "if there were any large and perceptible channels cominginto it from the kidneys the liquid would run out through these whenthe bladder was squeezed, in the same way that it entered?" Havingabruptly made these and similar remarks in precise and clear tones,he concluded by jumping up and departing - leaving me as though I werequite incapable of finding any plausible answer! 

The fact is that those who are enslaved to their sects are not merelydevoid of all sound knowledge, but they will not even stop to learn!Instead of listening, as they ought, to the reason why liquid canenter the bladder through the ureters, but is unable to go back againthe same way,- instead of admiring Nature's artistic skill - they refuseto learn; they even go so far as to scoff, and maintain that the kidneys,as well as many other things, have been made by Nature for no purpose!And some of them who had allowed themselves to be shown the ureterscoming from the kidneys and becoming implanted in the bladder, evenhad the audacity to say that these also existed for no purpose; and others said that they were spermatic ducts, and that this was whythey were inserted into the neck of the bladder and not into its cavity.When, therefore, we had demonstrated to them the real spermatic ductsentering the neck of the bladder lower down than the ureters, we supposedthat, if we had not done so before, we would now at least draw themaway from their false assumptions, and convert them forthwith to theopposite view. But even this they presumed to dispute, and said thatit was not to be wondered at that the semen should remain longer inthese latter ducts, these being more constricted, and that it shouldflow quickly down the ducts which came from the kidneys, seeing thatthese were well dilated. We were, therefore, further compelled toshow them in a still living animal, the urine plainly running outthrough the ureters into the bladder; even thus we hardly hoped tocheck their nonsensical talk. 

Now the method of demonstration is as follows. One has to divide theperitoneum in front of the ureters, then secure these with ligatures,and next, having bandaged up the animal, let him go (for he will notcontinue to urinate). After this one loosens the external bandages and shows the bladder empty and the ureters quite full and distended - in fact almost on the point of rupturing; on removing the ligaturefrom them, one then plainly sees the bladder becoming filled withurine. 

When this has been made quite clear, then, before the animal urinates,one has to tie a ligature round his penis and then to squeeze thebladder all over; still nothing goes back through the ureters to thekidneys. Here, then, it becomes obvious that not only in a dead animal,but in one which is still living, the ureters are prevented from receivingback the urine from the bladder. These observations having been made,one now loosens the ligature from the animal's penis and allows himto urinate, then again ligatures one of the ureters and leaves theother to discharge into the bladder. Allowing, then, some time toelapse, one now demonstrates that the ureter which was ligatured isobviously full and distended on the side next to the kidneys, whilethe other one - that from which the ligature had been taken - is itselfflaccid, but has filled the bladder with urine. Then, again, one mustdivide the full ureter, and demonstrate how the urine spurts out ofit, like blood in the operation of vene-section; and after this onecuts through the other also, and both being thus divided, one bandagesup the animal externally. Then when enough time seems to have elapsed,one takes off the bandages; the bladder will now be found empty, and the whole region between the intestines and the peritoneum full ofurine, as if the animal were suffering from dropsy. Now, if anyonewill but test this for himself on an animal, I think he will stronglycondemn the rashness of Asclepiades, and if he also learns the reasonwhy nothing regurgitates from the bladder into the ureters, I thinkhe will be persuaded by this also of the forethought and art shownby Nature in relation to animals. 

Now Hippocrates, who was the first known to us of all those who havebeen both physicians and philosophers in as much as he was the firstto recognize what Nature effects, expresses his admiration of her,and is constantly singing her praises and calling her "just." Alone,he says, she suffices for the animal in every respect, performingof her own accord and without any teaching all that is required. Beingsuch, she has, as he supposes, certain faculties, one attractive ofwhat is appropriate, and another eliminative of what is foreign, and she nourishes the animal, makes it grow, and expels its diseases bycrisis. Therefore he says that there is in our bodies a concordancein the movements of air and fluid, and that everything is in sympathy.According to Asclepiades, however, nothing is naturally in sympathywith anything else, all substance being divided and broken up intoinharmonious elements and absurd "molecules." Necessarily, then, besidesmaking countless other statements in opposition to plain fact, hewas ignorant of Nature's faculties, both that attracting what is appropriate,and that expelling what is foreign. Thus he invented some wretchednonsense to explain blood-production and anadosis, and, being utterlyunable to find anything to say regarding the clearing-out of superfluities,he did not hesitate to join issue with obvious facts, and, in thismatter of urinary secretion, to deprive both the kidneys and the uretersof their activity, by assuming that there were certain invisible channelsopening into the bladder. It was, of course, a grand and impressivething to do, to mistrust the obvious, and to pin one's faith in thingswhich could not be seen! 

Also, in the matter of the yellow bile, he makes an even grander and more spirited venture; for he says this is actually generated in the bile-ducts, not merely separated out. 

How comes it, then, that in cases of jaundice two things happen atthe same time - that the dejections contain absolutely no bile, and that the whole body becomes full of it? He is forced here again totalk nonsense, just as he did in regard to the urine. He also talksno less nonsense about the black bile and the spleen, not understanding what was said by Hippocrates; and he attempts in stupid - I might say insane - language, to contradict what he knows nothing about.

And what profit did he derive from these opinions from the point ofview of treatment? He neither was able to cure a kidney ailment, norjaundice, nor a disease of black bile, nor would he agree with theview held not merely by Hippocrates but by all men regarding drugs - that some of them purge away yellow bile, and others black, some againphlegm, and others the thin and watery superfluity; he held that allthe substances evacuated were produced by the drugs themselves, justas yellow bile is produced by the biliary passages! It matters nothing,according to this extraordinary man, whether we give a hydragogueor a cholagogue in a case of dropsy, for these all equally purge and dissolve the body, and produce a solution having such and such anappearance, which did not exist as such before! 

Must we not, therefore, suppose he was either mad, or entirely unacquaintedwith practical medicine? For who does not know that if a drug forattracting phlegm be given in a case of jaundice it will not evenevacuate four cyathi of phlegm? Similarly also if one of the hydragoguesbe given. A cholagogue, on the other hand, clears away a great quantityof bile, and the skin of patients so treated at once becomes clear.I myself have, in many cases, after treating the liver condition,then removed the disease by means of a single purgation; whereas,if one had employed a drug for removing phlegm one would have doneno good. 

Nor is Hippocrates the only one who knows this to be so, whilst thosewho take experience alone as their starting-point know otherwise;they, as well as all physicians who are engaged in the practice ofmedicine, are of this opinion. Asclepiades, however, is an exception;he would hold it a betrayal of his assumed "elements" to confess thetruth about such matters. For if a single drug were to be discoveredwhich attracted such and such a humour only, there would obviouslybe danger of the opinion gaining ground that there is in every bodya faculty which attracts its own particular quality. He thereforesays that safflower, the Cnidian berry, and Hippophaes, do not drawphlegm from the body, but actually make it. Moreover, he holds thatthe flower and scales of bronze, and burnt bronze itself, and germander,and wild mastich dissolve the body into water, and that dropsicalpatients derive benefit from these substances, not because they arepurged by them, but because they are rid of substances which actuallyhelp to increase the disease; for, if the medicine does not evacuatethe dropsical fluid contained in the body, but generates it, it aggravatesthe condition further. Moreover, scammony, according to the Asclepiadeanargument, not only fails to evacuate the bile from the bodies of jaundicedsubjects, but actually turns the useful blood into bile, and dissolvesthe body; in fact it does all manner of evil and increases the disease.

And yet this drug may be clearly seen to do good to numbers of people!"Yes," says he, "they derive benefit certainly, but merely in proportionto the evacuation."... But if you give these cases a drug which drawsoff phlegm they will not be benefited. This is so obvious that eventhose who make experience alone their starting-point are aware ofit; and these people make it a cardinal point of their teaching totrust to no arguments, but only to what can be clearly seen. In this,then, they show good sense; whereas Asclepiades goes far astray inbidding us distrust our senses where obvious facts plainly overturnhis hypotheses. Much better would it have been for him not to assailobvious facts, but rather to devote himself entirely to these.

Is it, then, these facts only which are plainly irreconcilable withthe views of Asclepiades? Is not also the fact that in summer yellowbile is evacuated in greater quantity by the same drugs, and in winterphlegm, and that in a young man more bile is evacuated, and in anold man more phlegm? Obviously each drug attracts something whichalready exists, and does not generate something previously non-existent.Thus if you give in the summer season a drug which attracts phlegmto a young man of a lean and warm habit, who has lived neither idlynor too luxuriously, you will with great difficulty evacuate a verysmall quantity of this humour, and you will do the man the utmostharm. On the other hand, if you give him a cholagogue, you will producean abundant evacuation and not injure him at all. 

Do we still, then, disbelieve that each drug attracts that humourwhich is proper to it? Possibly the adherents of Asclepiades willassent to this - or rather, they will - not possibly, but certainly-declare that they disbelieve it, lest they should betray their darlingprejudices. 

. Let us pass on, then, again to another piece of nonsense; forthe sophists do not allow one to engage in enquiries that are of anyworth, albeit there are many such; they compel one to spend one'stime in dissipating the fallacious arguments which they bring forward.

What, then, is this piece of nonsense? It has to do with the famous and far-renowned stone which draws iron [the lodestone]. It mightbe thought that this would draw their minds to a belief that thereare in all bodies certain faculties by which they attract their ownproper qualities. 

Now Epicurus, despite the fact that he employs in his "Physics" elementssimilar to those of Asclepiades, yet allows that iron is attractedby the lodestone, and chaff by amber. He even tries to give the causeof the phenomenon. His view is that the atoms which flow from thestone are related in shape to those flowing from the iron, and sothey become easily interlocked with one another; thus it is that,after colliding with each of the two compact masses (the stone and the iron) they then rebound into the middle and so become entangledwith each other, and draw the iron after them. So far, then, as hishypotheses regarding causation go, he is perfectly unconvincing; nevertheless,he does grant that there is an attraction. Further, he says that itis on similar principles that there occur in the bodies of animalsthe dispersal of nutriment and the discharge of waste matters, asalso the actions of cathartic drugs. 

Asclepiades, however, who viewed with suspicion the incredible characterof the cause mentioned, and who saw no other credible cause on thebasis of his supposed elements, shamelessly had recourse to the statementthat nothing is in any way attracted by anything else. Now, if hewas dissatisfied with what Epicurus said, and had nothing better tosay himself, he ought to have refrained from making hypotheses, and should have said that Nature is a constructive artist and that thesubstance of things is always tending towards unity and also towardsalteration because its own parts act upon and are acted upon by oneanother. For, if he had assumed this, it would not have been difficultto allow that this constructive Nature has powers which attract appropriate and expel alien matter. For in no other way could she be constructive,preservative of the animal, and eliminative of its diseases, unlessit be allowed that she conserves what is appropriate and dischargeswhat is foreign. 

But in this matter, too, Asclepiades realized the logical sequenceof the principles he had assumed; he showed no scruples, however,in opposing plain fact; he joins issue in this matter also, not merelywith all physicians, but with everyone else, and maintains that thereis no such thing as a crisis, or critical day, and that Nature doesabsolutely nothing for the preservation of the animal. For his constantaim is to follow out logical consequences and to upset obvious fact,in this respect being opposed to Epicurus; for the latter always statedthe observed fact, although he gives an ineffective explanation ofit. For, that these small corpuscles belonging to the lodestone rebound,and become entangled with other similar particles of the iron, and that then, by means of this entanglement (which cannot be seen anywhere)such a heavy substance as iron is attracted - I fail to understand how anybody could believe this. Even if we admit this, the same principlewill not explain the fact that, when the iron has another piece broughtin contact with it, this becomes attached to it. 

For what are we to say? That, forsooth, some of the particles thatflow from the lodestone collide with the iron and then rebound back,and that it is by these that the iron becomes suspended? that otherspenetrate into it, and rapidly pass through it by way of its emptychannels? that these then collide with the second piece of iron and are not able to penetrate it although they penetrated the first piece?and that they then course back to the first piece, and produce entanglementslike the former ones? 

The hypothesis here becomes clearly refuted by its absurdity. As amatter of fact, I have seen five writing-stylets of iron attachedto one another in a line, only the first one being in contact withthe lodestone, and the power being transmitted through it to the others.Moreover, it cannot be said that if you bring a second stylet intocontact with the lower end of the first, it becomes held, attached,and suspended, whereas, if you apply it to any other part of the sideit does not become attached. For the power of the lodestone is distributedin all directions; it merely needs to be in contact with the firststylet at any point; from this stylet again the power flows, as quickas a thought, all through the second, and from that again to the third.Now, if you imagine a small lodestone hanging in a house, and in contactwith it all round a large number of pieces of iron, from them againothers, from these others, and so on,- all these pieces of iron mustsurely become filled with the corpuscles which emanate from the stone;therefore, this first little stone is likely to become dissipatedby disintegrating into these emanations. Further, even if there beno iron in contact with it, it still disperses into the air, particularlyif this be also warm. 

"Yes," says Epicurus, "but these corpuscles must be looked on as exceedinglysmall, so that some of them are a ten-thousandth part of the sizeof the very smallest particles carried in the air." Then do you ventureto say that so great a weight of iron can be suspended by such smallbodies? If each of them is a ten-thousandth part as large as the dustparticles which are borne in the atmosphere, how big must we supposethe hook-like extremities by which they interlock with each otherto be? For of course this is quite the smallest portion of the wholeparticle. 

Then, again, when a small body becomes entangled with another smallbody, or when a body in motion becomes entangled with another alsoin motion, they do not rebound at once. For, further, there will ofcourse be others which break in upon them from above, from below,from front and rear, from right and left, and which shake and agitatethem and never let them rest. Moreover, we must perforce suppose thateach of these small bodies has a large number of these hook-like extremities.For by one it attaches itself to its neighbours, by another - the top most one - to the lodestone, and by the bottom one to the iron. For if itwere attached to the stone above and not interlocked with the ironbelow, this would be of no use. Thus, the upper part of the superiorextremity must hang from the lodestone, and the iron must be attachedto the lower end of the inferior extremity; and, since they interlockwith each other by their sides as well, they must, of course, havehooks there too. Keep in mind also, above everything, what small bodiesthese are which possess all these different kinds of outgrowths. Stillmore, remember how, in order that the second piece of iron may becomeattached to the first, the third to the second, and to that the fourth,these absurd little particles must both penetrate the passages inthe first piece of iron and at the same time rebound from the piececoming next in the series, although this second piece is naturallyin every way similar to the first. 

Such an hypothesis, once again, is certainly not lacking in audacity;in fact, to tell the truth, it is far more shameless than the previousones; according to it, when five similar pieces of iron are arrangedin a line, the particles of the lodestone which easily traverse thefirst piece of iron rebound from the second, and do not pass readilythrough it in the same way. Indeed, it is nonsense, whichever alternativeis adopted. For, if they do rebound, how then do they pass throughinto the third piece? And if they do not rebound, how does the secondpiece become suspended to the first? For Epicurus himself looked onthe rebound as the active agent in attraction. 

But, as I have said, one is driven to talk nonsense whenever one getsinto discussion with such men. Having, therefore, given a concise and summary statement of the matter, I wish to be done with it. Forif one diligently familiarizes oneself with the writings of Asclepiades,one will see clearly their logical dependence on his first principles,but also their disagreement with observed facts. Thus, Epicurus, inhis desire to adhere to the facts, cuts an awkward figure by aspiringto show that these agree with his principles, whereas Asclepiadessafeguards the sequence of principles, but pays no attention to theobvious fact. Whoever, therefore, wishes to expose the absurdity oftheir hypotheses, must, if the argument be in answer to Asclepiades,keep in mind his disagreement with observed fact; or if in answerto Epicurus, his discordance with his principles. Almost all the othersects depending on similar principles are now entirely extinct, whilethese alone maintain a respectable existence still. Yet the tenetsof Asclepiades have been unanswerably confuted by Menodotus the Empiricist,who draws his attention to their opposition to phenomena and to eachother; and, again, those of Epicurus have been confuted by Asclepiades,who adhered always to logical sequence, about which Epicurus evidentlycares little. 

Now people of the present day do not begin by getting a clear comprehensionof these sects, as well as of the better ones, thereafter devotinga long time to judging and testing the true and false in each of them;despite their ignorance, they style themselves, some "physicians"and others "philosophers." No wonder, then, that they honour the falseequally with the true. For everyone becomes like the first teacherthat he comes across, without waiting to learn anything from anybodyelse. And there are some of them, who, even if they meet with morethan one teacher, are yet so unintelligent and slow-witted that evenby the time they have reached old age they are still incapable of understanding the steps of an argument.... In the old days such peopleused to be set to menial tasks.... What will be the end of it Godknows! 

Now, we usually refrain from arguing with people whose principlesare wrong from the outset. Still, having been compelled by the naturalcourse of events to enter into some kind of a discussion with them,we must add this further to what was said - that it is not only catharticdrugs which naturally attract their special qualities, but also thosewhich remove thorns and the points of arrows such as sometimes becomedeeply embedded in the flesh. Those drugs also which draw out animalpoisons or poisons applied to arrows all show the same faculty asdoes the lodestone. Thus, I myself have seen a thorn which was embeddedin a young man's foot fail to come out when we exerted forcible tractionwith our fingers, and yet come away painlessly and rapidly on theapplication of a medicament. Yet even to this some people will object,asserting that when the inflammation is dispersed from the part thethorn comes away of itself, without being pulled out by anything.But these people seem, in the first place, to be unaware that thereare certain drugs for drawing out inflammation and different onesfor drawing out embedded substances; and surely if it was on the cessationof an inflammation that the abnormal matters were expelled, then alldrugs which disperse inflammations ought ipso facto; to possess thepower of extracting these substances as well. 

And secondly, these people seem to be unaware of a still more surprisingfact, namely, that not merely do certain medicaments draw out thornsand others poisons, but that of the latter there are some which attractthe poison of the viper, others that of the sting-ray, and othersthat of some other animal; we can, in fact, plainly observe thesepoisons deposited on the medicaments. Here, then, we must praise Epicurusfor the respect he shows towards obvious facts, but find fault withhis views as to causation. For how can it be otherwise than extremelyfoolish to suppose that a thorn which we failed to remove by digitaltraction could be drawn out by these minute particles? 

Have we now, therefore, convinced ourselves that everything whichexists possesses a faculty by which it attracts its proper quality,and that some things do this more, and some less? 

Or shall we also furnish our argument with the illustration affordedby corn? For those who refuse to admit that anything is attractedby anything else, will, I imagine, be here proved more ignorant regardingNature than the very peasants. When, for my own part, I first learnedof what happens, I was surprised, and felt anxious to see it withmy own eyes. Afterwards, when experience also had confirmed its truth,I sought long among the various sects for an explanation, and, withthe exception of that which gave the first place to attraction, Icould find none which even approached plausibility, all the othersbeing ridiculous and obviously quite untenable. 

What happens, then, is the following. When our peasants are bringingcorn from the country into the city in wagons, and wish to filch someaway without being detected, they fill earthen jars with water and stand them among the corn; the corn then draws the moisture into itselfthrough the jar and acquires additional bulk and weight, but the factis never detected by the onlookers unless someone who knew about thetrick before makes a more careful inspection. Yet, if you care toset down the same vessel in the very hot sun, you will find the dailyloss to be very little indeed. Thus corn has a greater power thanextreme solar heat of drawing to itself the moisture in its neighbourhood.Thus the theory that the water is carried towards the rarefied partof the air surrounding us (particularly when that is distinctly warm)is utter nonsense; for although it is much more rarefied there thanit is amongst the corn, yet it does not take up a tenth part of themoisture which the corn does. 

. Since, then, we have talked sufficient nonsense - not willingly,but because we were forced, as the proverb says, "to behave madlyamong madmen"- let us return again to the subject of urinary secretion.Here let us forget the absurdities of Asclepiades, and, in companywith those who are persuaded that the urine does pass through thekidneys, let us consider what is the character of this function. For,most assuredly, either the urine is conveyed by its own motion tothe kidneys, considering this the better course (as do we when wego off to market!), or, if this be impossible, then some other reasonfor its conveyance must be found. What, then, is this? If we are notgoing to grant the kidneys a faculty for attracting this particularquality, as Hippocrates held, we shall discover no other reason. For,surely everyone sees that either the kidneys must attract the urine,or the veins must propel it - if, that is, it does not move of itself.But if the veins did exert a propulsive action when they contract,they would squeeze out into the kidneys not merely the urine, butalong with it the whole of the blood which they contain. And if thisis impossible, as we shall show, the remaining explanation is thatthe kidneys do exert traction. 

And how is propulsion by the veins impossible? The situation of thekidneys is against it. They do not occupy a position beneath the hollowvein [vena cava] as does the sieve-like [ethmoid] passage in the nose and palate in relation to the surplus matter from the brain; theyare situated on both sides of it. Besides, if the kidneys are likesieves, and readily let the thinner serous [whey-like] portion through,and keep out the thicker portion, then the whole of the blood containedin the vena cava must go to them, just as the whole of the wine isthrown into the filters. Further, the example of milk being made intocheese will show clearly what I mean. For this, too, although it isall thrown into the wicker strainers, does not all percolate through;such part of it as is too fine in proportion to the width of the meshespasses downwards, and this is called whey [serum]; the remaining thickportion which is destined to become cheese cannot get down, sincethe pores of the strainers will not admit it. Thus it is that, ifthe blood-serum has similarly to percolate through the kidneys, thewhole of the blood must come to them, and not merely one part of it.

What, then, is the appearance as found on dissection? One division of the vena cava is carried upwards to the heart, and the other mounts upon the spine and extends along its whole lengthas far as the legs; thus one division does not even come near thekidneys, while the other approaches them but is certainly not insertedinto them. Now, if the blood were destined to be purified by themas if they were sieves, the whole of it would have to fall into them,the thin part being and the thick part retained above. But, as a matterof fact, this is not so. For the kidneys lie on either side of thevena cava. They therefore do not act like sieves, filtering fluidsent to them by the vena cava, and themselves contributing no force.They obviously exert traction; for this is the only remaining alternative.

How, then, do they exert this traction? If, as Epicurus thinks, allattraction takes place by virtue of the rebounds and entanglementsof atoms, it would be certainly better to maintain that the kidneyshave no attractive action at all; for his theory, when examined, wouldbe found as it stands to be much more ridiculous even than the theoryof the lodestone, mentioned a little while ago. Attraction occursin the way that Hippocrates laid down; this will be stated more clearlyas the discussion proceeds; for the present our task is not to demonstratethis, but to point out that no other cause of the secretion of urinecan be given except that of attraction by the kidneys, and that thisattraction does not take place in the way imagined by people who donot allow Nature a faculty of her own. 

For if it be granted that there is any attractive faculty at all inthose things which are governed by Nature, a person who attemptedto say anything else about the absorption of nutriment would be considereda fool. 

. Now, while Erasistratus for some reason replied at great lengthto certain other foolish doctrines, he entirely passed over the viewheld by Hippocrates, not even thinking it worth while to mention it,as he did in his work "On Deglutition"; in that work, as may be seen,he did go so far as at least to make mention of the word attraction,writing somewhat as follows: 

"Now, the stomach does not appear to exercise any attraction." Butwhen he is dealing with anadosis he does not mention the Hippocraticview even to the extent of a single syllable. Yet we should have beensatisfied if he had even merely written this: "Hippocrates lies insaying 'The flesh attracts both from the stomach and from without,'for it cannot attract either from the stomach or from without." Orif he had thought it worth while to state that Hippocrates was wrongin criticizing the weakness of the neck of the uterus, "seeing thatthe orifice of the uterus has no power of attracting semen," or ifhe [Erasistratus] had thought proper to write any other similar opinion,then we in our turn would have defended ourselves in the followingterms: 

"My good sir, do not run us down in this rhetorical fashion withoutsome proof; state some definite objection to our view, in order thateither you may convince us by a brilliant refutation of the ancientdoctrine, or that, on the other hand, we may convert you from yourignorance." Yet why do I say "rhetorical"? For we too are not to supposethat when certain rhetoricians pour ridicule upon that which theyare quite incapable of refuting, without any attempt at argument,their words are really thereby constituted rhetoric. For rhetoricproceeds by persuasive reasoning; words without reasoning are buffooneryrather than rhetoric. Therefore, the reply of Erasistratus in histreatise "On Deglutition" was neither rhetoric nor logic. For whatis it that he says? "Now, the stomach does not appear to exerciseany traction." Let us testify against him in return, and set our argumentbeside his in the same form. Now, there appears to be no peristalsisof the gullet. "And how does this appear?" one of his adherents mayperchance ask. "For is it not indicative of peristalsis that alwayswhen the upper parts of the gullet contract the lower parts dilate?"Again, then, we say, "And in what way does the attraction of the stomachnot appear? For is it not indicative of attraction that always whenthe lower parts of the gullet dilate the upper parts contract?" Now,if he would but be sensible and recognize that this phenomenon isnot more indicative of the one than of the other view, but that itapplies equally to both, we should then show him without further delaythe proper way to the discovery of truth. 

We will, however, speak about the stomach again. And the dispersalof nutriment [anadosis] need not make us have recourse to the theoryregarding the natural tendency of a vacuum to become refilled, whenonce we have granted the attractive faculty of the kidneys. Now, althoughErasistratus knew that this faculty most certainly existed, he neithermentioned it nor denied it, nor did he make any statement as to hisviews on the secretion of urine. 

Why did he give notice at the very beginning of his "General Principles"that he was going to speak about natural activities - firstly whatthey are, how they take place, and in what situations - and then, inthe case of urinary secretion, declared that this took place throughthe kidneys, but left out its method of occurrence? It must, then,have been for no purpose that he told us how digestion occurs, orspends time upon the secretion of biliary superfluities; for in thesecases also it would have been sufficient to have named the parts throughwhich the function takes place, and to have omitted the method. Onthe contrary, in these cases he was able to tell us not merely throughwhat organs, but also in what way it occurs - as he also did, I think,in the case of anadosis; for he was not satisfied with saying thatthis took place through the veins, but he also considered fully themethod, which he held to be from the tendency of a vacuum to becomerefilled. Concerning the secretion of urine, however, he writes thatthis occurs through the kidneys, but does not add in what way it occurs.I do not think he could say that this was from the tendency of matterto fill a vacuum, for, if this were so, nobody would have ever diedof retention of urine, since no more can flow into a vacuum than hasrun out. For, if no other factor comes into operation save only thistendency by which a vacuum becomes refilled, no more could ever flowin than had been evacuated. Nor, could he suggest any other plausiblecause, such, for example, as the of nutriment by the stomach whichoccurs in the process of anadosis; this had been entirely disprovedin the case of blood in the vena cava; it is excluded, not merelyowing to the long distance, but also from the fact that the overlyingheart, at each diastole, robs the vena cava by violence of a considerablequantity of blood. 

In relation to the lower part of the vena cava there would still remain,solitary and abandoned, the specious theory concerning the fillingof a vacuum. This, however, is deprived of plausibility by the factthat people die of retention of urine, and also, no less, by the situationof the kidneys. For, if the whole of the blood were carried to thekidneys, one might properly maintain that it all undergoes purificationthere. But, as a matter of fact, the whole of it does not go to them,but only so much as can be contained in the veins going to the kidneys;this portion only, therefore, will be purified. Further, the thinserous part of this will pass through the kidneys as if through asieve, while the thick sanguineous portion remaining in the veinswill obstruct the blood flowing in from behind; this will first, therefore,have to run back to the vena cava, and so to empty the veins goingto the kidneys; these veins will no longer be able to conduct a secondquantity of unpurified blood to the kidneys - occupied as they areby the blood which had preceded, there is no passage left. What powerhave we, then, which will draw back the purified blood from the kidneys?And what power,in the next place, will bid this blood retire to thelower part of the vena cava, and will enjoin on another quantity comingfrom above not to proceed downwards before turning off into the kidneys?

Now Erasistratus realized that all these ideas were open to many objections,and he could only find one idea which held good in all respects - namely,that of attraction. Since, therefore, he did not wish either to getinto difficulties or to mention the view of Hippocrates, he deemedit better to say nothing at all as to the manner in which secretionoccurs. 

But even if he kept silence, I am not going to do so. For I know thatif one passes over the Hippocratic view and makes some other pronouncementabout the function of the kidneys, one cannot fall to make oneselfutterly ridiculous. It was for this reason that Erasistratus keptsilence and Asclepiades lied; they are like slaves who have had plentyto say in the early part of their career, and have managed by excessiverascality to escape many and frequent accusations, but who, later,when caught in the act of thieving, cannot find any excuse; the moremodest one then keeps silence, as though thunderstruck, whilst themore shameless continues to hide the missing article beneath his armand denies on oath that he has ever seen it. For it was in this wayalso that Asclepiades, when all subtle excuses had failed him and there was no longer any room for nonsense about "conveyance towardsthe rarefied part [of the air]," and when it was impossible withoutincurring the greatest derision to say that this superfluity [i.e.the urine] is generated by the kidneys as is bile by the canals inthe liver - he, then, I say, clearly lied when he swore that the urinedoes not reach the kidneys, and maintained that it passes, in theform of vapour, straight from the region of the vena cava, to collectin the bladder. 

Like slaves, then, caught in the act of stealing, these two are quitebewildered, and while the one says nothing, the other indulges inshameless lying. 

. Now such of the younger men as have dignified themselves withthe names of these two authorities by taking the appellations "Erasistrateans"or "Asclepiadeans" are like the Davi and Getae - the slaves introducedby the excellent Menander into his comedies. As these slaves heldthat they had done nothing fine unless they had cheated their masterthree times, so also the men I am discussing have taken their timeover the construction of impudent sophisms, the one party strivingto prevent the lies of Asclepiades from ever being refuted, and theother saying stupidly what Erasistratus had the sense to keep silenceabout. 

But enough about the Asclepiadeans. The Erasistrateans, in attemptingto say how the kidneys let the urine through, will do anything orsuffer anything or try any shift in order to find some plausible explanationwhich does not demand the principle of attraction. 

Now those near the times of Erasistratus maintain that the parts abovethe kidneys receive pure blood, whilst the watery residue, being heavy,tends to run downwards; that this, after percolating through the kidneysthemselves, is thus rendered serviceable, and is sent, as blood, toall the parts below the kidneys. 

For a certain period at least this view also found favour and flourished,and was held to be true; after a time, however, it became suspectto the Erasistrateans themselves, and at last they abandoned it. Forapparently the following two points were assumed, neither of whichis conceded by anyone, nor is even capable of being proved. The firstis the heaviness of the serous fluid, which was said to be producedin the vena cava, and which did not exist, apparently, at the beginning,when this fluid was being carried up from the stomach to the liver.Why, then, did it not at once run downwards when it was in these situations?And if the watery fluid is so heavy, what plausibility can anyonefind in the statement that it assists in the process of anadosis?

In the second place there is this absurdity, that even if it be agreedthat all the watery fluid does fall downwards, and only when it isin the vena cava, still it is difficult, or, rather, impossible, tosay through what means it is going to fall into the kidneys, seeingthat these are not situated below, but on either side of the venacava, and that the vena cava is not inserted into them, but merelysends a branch into each of them, as it also does into all the otherparts. 

What doctrine, then, took the place of this one when it was condemned?One which to me seems far more foolish than the first, although italso flourished at one time. For they say, that if oil be mixed withwater and poured upon the ground, each will take a different route,the one flowing this way and the other that, and that, therefore,it is not surprising that the watery fluid runs into the kidneys,while the blood falls downwards along the vena cava. Now this doctrinealso stands already condemned. For why, of the countless veins whichspring from the vena cava, should blood flow into all the others,and the serous fluid be diverted to those going to the kidneys? Theyhave not answered the question which was asked; they merely statewhat happens and imagine they have thereby assigned the reason.

Once again, then (the third cup to the Saviour!), let us now speakof the worst doctrine of all, lately invented by Lycus of Macedonia,but which is popular owing to its novelty. This Lycus, then, maintains,as though uttering an oracle from the inner sanctuary, that urineis residual matter from the nutrition of the kidneys! Now, the amountof urine passed every day shows clearly that it is the whole of thefluid drunk which becomes urine, except for that which comes awaywith the dejections or passes off as sweat or insensible perspiration.This is most easily recognized in winter in those who are doing nowork but are carousing, especially if the wine be thin and diffusible;these people rapidly pass almost the same quantity as they drink.And that even Erasistratus was aware of this is known to those whohave read the first book of his "General Principles." Thus Lycus isspeaking neither good Erasistratism, nor good Asclepiadism, far lessgood Hippocratism. He is, therefore, as the saying is, like a whitecrow, which cannot mix with the genuine crows owing to its colour,nor with the pigeons owing to its size. For all this, however, heis not to be disregarded; he may, perhaps, be stating some wonderfultruth, unknown to any of his predecessors. 

Now it is agreed that all parts which are undergoing nutrition producea certain amount of residue, but it is neither agreed nor is it likely,that the kidneys alone, small bodies as they are, could hold fourwhole congii, and sometimes even more, of residual matter. For thissurplus must necessarily be greater in quantity in each of the largerviscera; thus, for example, that of the lung, if it corresponds inamount to the size of the viscus, will obviously be many times morethan that in the kidneys, and thus the whole of the thorax will becomefilled, and the animal will be at once suffocated. But if it be saidthat the residual matter is equal in amount in each of the other parts,where are the bladders, one may ask, through which it is excreted?For, if the kidneys produce in drinkers three and sometimes four congiiof superfluous matter, that of each of the other viscera will be muchmore, and thus an enormous barrel will be needed to contain the wasteproducts of them all. Yet one often urinates practically the samequantity as one has drunk, which would show that the whole of whatone drinks goes to the kidneys. 

Thus the author of this third piece of trickery would appear to haveachieved nothing, but to have been at once detected, and there stillremains the original difficulty which was insoluble by Erasistratus and by all others except Hippocrates. I dwell purposely on this topic,knowing well that nobody else has anything to say about the functionof the kidneys, but that either we must prove more foolish than thevery butchers if we do not agree that the urine passes through thekidneys; or, if one acknowledges this, that then one cannot possiblygive any other reason for the secretion than the principle of attraction.

Now, if the movement of urine does not depend on the tendency of avacuum to become refilled, it is clear that neither does that of theblood nor that of the bile; or if that of these latter does so, thenso also does that of the former. For they must all be accomplishedin one and the same way, even according to Erasistratus himself.

This matter, however, will be discussed more fully in the book followingthis.