by Aristotle
There is also to be explained in either case the cause of the motion of the gills and of the lungs, the rise and fall of which effects the admission and expulsion of the breath or of water. The following, moreover, is the manner of the constitution of the [15] organ.
26(20) · In connexion with the heart there are three phenomena, which, though apparently of the same nature, are really not so, namely palpitation, pulsation, and respiration.
Palpitation is the rushing together of the hot substance in the heart owing to the chilling influence of residual or waste products. It occurs, for example, in the [20] ailment known as spasms and in other diseases. It occurs also in fear, for when one is afraid the upper parts become cold, and the hot substance, fleeing away, by its concentration in the heart produces palpitation. It is crushed into so small a space that sometimes life is extinguished, and the animals die of the fright and morbid [25] disturbance.
The beating of the heart, which, as can be seen, goes on continuously, is similar to the throbbing of an abscess. That, however, is accompanied by pain, because the change produced in the blood is unnatural, and it goes on until the matter formed by concoction is discharged. There is a similarity between this phenomenon and that of [30] boiling; for boiling is due to the volatilization of fluid by heat and the expansion consequent on increase of bulk. But in an abscess, if there is no evaporation through [480a1] the walls, the process terminates in suppuration due to the thickening of the liquid, while in boiling it ends in the escape of the fluid out of the containing vessel.
In the heart the beating is produced by the heat expanding the fluid, of which the food furnishes a constant supply. It occurs when the fluid rises to the outer wall [5] of the heart, and it goes on continuously; for there is a constant flow of the fluid that goes to constitute the blood, it being in the heart that the blood is first created. That this is so we can perceive in the initial stages of generation, for the heart can be seen to contain blood before the veins become distinct. This explains why pulsation in [10] youth exceeds that in older people, for in the young the exhalation is more abundant.
All the veins pulse, and do so simultaneously with each other, owing to their connexion with the heart. The heart always beats, and hence they also beat continuously and simultaneously with each other and with it.
Palpitation, then, is the recoil of the heart against the compression due to cold; [15] and pulsation is the volatilization of the heated fluid.
27(21) · Respiration takes place when the hot substance which is the seat of the nutritive principle increases. For it, like the rest of the body, requires nutrition, and more so than the other parts, for it is through it that they are nourished. But when it increases it necessarily causes the organ to rise. This organ [20] we must take to be constructed like the bellows in a smithy, for both heart and lungs conform pretty well to this shape. Such a structure must be double, for the nutritive principle must be situated in the centre of the cooling force.
Thus on increase of bulk expansion results, which necessarily causes the surrounding parts to rise. Now this can be seen to occur when people respire; they [25] raise their chest because the principle of the organ described resident within the chest causes an identical expansion of this organ. When it dilates the outer air, being cold, must rush in as into a bellows, and by its chilling influence reduce by [480b1] extinction the excess of the fire. But, as the increase of bulk causes the organ to dilate, so diminution causes contraction, and when it collapses the air which entered must pass out again. When it enters the air is cold, but on issuing it is warm owing to [5] its contact with the heat resident in this organ, and this is specially the case in those animals that possess a full-blooded lung. The numerous canal-like ducts in the lung, into which it passes, have each a blood-vessel lying alongside, so that the whole lung is thought to be full of blood. The inward passage of the air is called respiration, the [10] outward expiration, and this double movement goes on continuously just so long as the animal lives and keeps this organ in continuous motion; it is for this reason that life depends on the passage of the breath outwards and inwards.
It is in the same way that the motion of the gills in fishes takes place. When the [15] hot substance in the blood throughout the members rises, the gills rise too, and let the water pass through, but when it is chilled and retreats through its channels to the heart, they contract and eject the water. As the heat in the heart continually rises, so the heart continually receives it and expels it again when it is chilled. Hence, as in respiring animals life and death depend on respiration, so in the other animals they depend on the admission of water. [20]
Our discussion of life and death and kindred topics is now practically complete. But as to health and disease, not only the physician but also the natural scientist must, up to a point, give an account of their causes. The extent to which these two differ and investigate diverse provinces must not escape us, since facts [25] show that their inquiries are, to a certain extent, at least co-terminous. For those physicians who are cultivated and learned make some mention of natural science, and claim to derive their principles from it, while the most accomplished investigators into nature generally push their studies so far as to conclude with an account of medical principles. [30]
**TEXT: W. D. Ross, Aristotle: Parva Naturalia, Clarendon Press, Oxford, 1955
1The clepsydra was a device for lifting small quantities of liquid, similar in operation to the modern pipette.
2Retaining φυτῶν.
ON BREATH**
J. F. Dobson
[481a1] 1 · What is the mode of growth of the natural breath and its mode of maintenance? For we see that it increases in volume and strength in accordance with both changes of age and the varying condition of the body. May we suppose that it increases as the other parts do, through the addition of some substance to it? [5] Now it is nutriment that is thus added to living creatures; so that we must consider the nature and origin of the nutriment in this case.
Nutrition may result in either of two ways—by means of respiration, or, as in the case of the other parts of the body, by the digestive process consequent on the introduction of the nutriment; and of the two the process by means of the nutriment is perhaps the more likely; for body is nourished by body, and the breath is of the nature of body.
[10] What then is the method? Clearly we must suppose that the breath is nourished by drawing and digesting nutriment from the vein-system, for the blood is the ultimate and universal nutriment. So the breath receives nutriment into the hot element as into its vessel and receptacle.1
The air draws the nutriment and imparts the activity, and applying to itself the [15] digestive power is the cause of its own growth and nutrition.
Perhaps there is nothing absurd in this, but rather in the proposition that the breath is originally derived from the nutriment; for that which is akin to the soul is purer—unless we were to say that the soul itself is a later product than the body, arising when the seeds are sorted out and move towards the development of their nature.
[20] Again, if2 there is some residue left from all nutriment, by what passage is it ejected in this case? It is not reasonable to suppose that it is by the process of exhalation, for this succeeds immediately to the inhalation. Clearly there remains only the explanation that it is through the ducts of the wind-pipe.
The residue which is secreted from it must be either finer or coarser; in either case there is a grave difficulty, if the breath is assumed to be the purest of all substances. But if it is coarser we shall have to assume that there are certain ducts of larger size.
The assumption that we take in and expel the breath by the same ducts is again [25] strange and unreasonable.
Such then are the questions raised by the theory that the breath is maintained and increased by nutriment.
2 · Aristogenes supposes that the growth of the breath is due to respiration, the air being digested in the lungs; for the breath, he holds, is also a form of nutriment, and
is distributed into the various vessels, and the refuse is ejected [30] again.
This theory involves more difficulties, for what can cause this digestion? [481b1] Apparently the breath digests itself, as it digests other things; but this is strange intrinsically, unless the breath is different from the external air. If it is different, perhaps the bodily warmth in it may cause digestion.
However, it may be reasonably maintained that the breath3 is coarser than the [5] outside air, since it is combined with the moisture from the vessels and from the solid parts in general; so that digestion will be a process towards corporeality; but the theory that it is finer is not convincing.
Moreover, the rapidity of its digestion is contrary to reason; for the exhalation follows immediately on the inhalation. What then is the agent which so quickly changes and modifies it? [10]
We must naturally suppose that it is the warmth of the body, and the evidence of sense supports this, for the air when exhaled is warm.
Again, if the substance which is digested is in the lungs and the wind-pipe, the active warmth must also reside there: but the common view is that it is not so, but that the nutriment is evaporated by the motion of the breath.
It is still more astonishing if the breath in process of digestion attracts the warmth to itself or receives it because some other agent sets it in motion; moreover, [15] on this theory it is not in itself the primary moving cause.
Then again, respiration extends as far as the lungs only, as the followers of Aristogenes themselves state; but the natural breath is distributed throughout the whole body. If it is from the lungs that the breath is distributed to all parts of the body, including those lower than the lungs, how can the process of its digestion be so [20] rapid? This is more remarkable and involves a greater difficulty; for the lungs cannot distribute the air to the lower parts during the actual process of its digestion. And yet to some extent it would seem that this must be the case, if the digestion takes place in the lungs, and the lower parts also are affected by the respiration.
But the conclusion in this case is still more remarkable and important[25]—namely that the digestion is effected, as it were, entirely by transit and contact.
This also is unreasonable, and still more untenable,4 since it assumes that the same duct is used by the nutriment and the excretions; while if we assume that digestion is effected by any of the other internal parts, the objections already stated will apply: unless we were to assume that excrement is not formed from all [482a1] nutriment, nor in all animals, any more than in plants, for we cannot find it in every one of the bodily parts, or even if we do, at least not in all animals.5
But according to this view the vessels grow just like the other parts, and as they [5] become broadened and distended, the volume of air which flows in and out is increased: and if there must inevitably be some air contained in them, the actual question which we are now asking,6 ‘What is the air which naturally exists in them; and how does this increase under healthy conditions?’ will be obvious from the preceding statement.
How is the natural breath nourished and developed in the case of creatures which have not respiration? For in their case the nutriment can no longer come from without. If in the former case it was from forces within, and from the common [10] nutriment of the body, it is reasonable to say that the same is true in their case also, for similar effects come in like manner from the same causes—unless really in the case of these creatures too it is from without, like their perception of smell; but then they must have some process similar to respiration.7
Under this head we might raise the question whether such creatures can truly be called non-respiratory—pointing to this argument and also to the way in which [15] they take in nutriment; for we should say that they must draw in some breath at the same time; and we should further urge that they must respire for the sake of refrigeration, which they must require just as other creatures do.
But if in their case the refrigeration takes place through the diaphragm, it is clear that the entry of the air must also be by the same pressure; so that there is some process similar to respiration.
But it cannot be determined how or by what agency the air is drawn in; or if [20] there is a drawing in, how the entry takes place—unless, indeed, it is spontaneous. This is a subject for separate investigation.
But how is the natural breath nourished and increased in the case of creatures that live in the water? Apart from their inability to respire, we say further that air cannot exist in water: so it only remains to say that in their case it is by means of the food: and so either all creatures are not uniform in their methods, or else in the case [25] of the others also it is by means of the food. Such are the three possible theories, of which one must be right. So much, then, as regards the nutrition and growth of the breath.
3 · With regard to respiration, some philosophers—such as Empedocles and Democritus—do not deal with its purpose, but only describe the process; others do [30] not even deal with the process at all, but assume it as obvious. But we ought further to make it quite clear whether its purpose is refrigeration. For if the bodily heat is inherent in the upper parts, it follows that the lower parts would have no need of refrigeration: but as a matter of fact the innate breath pervades the whole body, and its origin is from the lungs.
The inspired breath also is thought to be distributed uniformly over all parts, so that it remains to be proved that this is not the case. [35]
Again, it is strange if the lower parts do not require some motive force and, as it were, some nutriment. And it would no longer be for the sake of refrigeration, if it [482b1] does pervade the whole.
Further, the process of the breath’s distribution in general is imperceptible, and so is its speed; and again, the matter of its counter-flow, if, as assumed, it is from all parts, is remarkable, unless it flows back from the most remote parts in some different way, while in its proper and primary sense the action takes place [5] from the regions about the heart.
In many instances such a want of symmetry in functions and faculties may be observed.
However, it is at any rate8 strange if breath is distributed even into the bones—for they say that this is the case, and that it passes there from the air-ducts. Therefore, as I have shown, we must consider the respiration—its purpose, and the parts which it affects, and how it affects them. Again, nutriment is not carried by [10] the air-ducts to all parts, for instance to the vessels themselves and certain other parts; but nevertheless plants live and receive nourishment.9 This question belongs rather to a treatise on methods of nutrition.
4 · Whereas there are three motions belonging to the breath in the windpipe—respiration, pulsation, and a third which introduces and assimilates the [15] nutriment—we must define how and where and for what purpose each takes place.
Of these, the motion of the pulse is perceptible by the senses wherever we touch the body. That of the respiration is perceptible up to a certain point, but is recognized in the majority of parts by a reasoning process. That of nutrition is in practically all parts determinable by reasoning, but by sense in so far as it can be [20] observed from its results.
Now clearly the respiration has its motive principle from the inward parts, whether we ought to call this principle a power of the soul, the soul, or some other combination of bodies which through their agency causes this attraction, and the nutritive faculty would seem to be caused by the respiration, for the respiration [25] corresponds to it, and is in reality similar to it. And to discover whether the whole body is not uniform with regard to the time taken by such motion, or whether there is no difference as to its simultaneity, we must consider all the parts.10
The pulse is something peculiar and distinct from the other motions and in some respects may be seen to be contingent, assuming that when there is an excess [30] of warmth in a fluid, that fluid which is evaporated must set up a pulsation owing to the air being intercepted in the interior, and pulsation must arise in the originating part a
nd in the earliest stage, since it is inborn in the earliest parts. For it arises firstly and in the greatest degree in the heart, and thence extends to the other parts.11 Perhaps this must be an inseparable consequence of the essential nature [35] underlying the living creature, which is manifested when the creature is in a condition of activity.
That the pulse has no connexion with the respiration is shown by the following [483a1] indication—whether one breathes quickly or regularly, violently or gently, the pulse remains the same and unchanged, but it becomes irregular and spasmodic owing to certain bodily affections and in consequence of fear, hope, and anguish affecting the soul.
[5] Next we ought to consider whether the pulse occurs also in the arteries and with the same rhythm and regularity. This does not appear to be so in the case of parts widely separated, and, as has been noted, it seems to serve no purpose whatsoever.
For, on the other hand, the respiration and reception of food, whether they are [10] regarded as quite independent or as correlated, clearly exist for a purpose, and admit of rational explanation.
And of the three, we may reasonably say that the pulsatory and respiratory motions are prior to the other, for nutrition assumes their pre-existence. Or is this not so? for respiration begins when the young is separated from the mother; the reception of nutriment, and nutrition, occur both while the embryo is forming and [15] after it is formed; but the pulsation occurs at the earliest stage, as soon as the heart begins to form, as is evident in the case of eggs. So the pulse comes first, and resembles an activity and not an interception of the breath, unless that also can conduce towards its activity.
5 · They say that the breath which is respired is carried into the belly, not [20] through the gullet—that is impossible—but there is a duct along the loins through which the breath is carried by the respiration from the trachea into the belly and out again: and this can be perceived by the sense.