The Politics of Aristotle

by Aristotle

  Both plants and animals perish if not fed, for in that case they consume themselves; just as a large flame consumes and burns up a small one by using up its [30] nutriment, so the natural warmth which is the primary cause of digestion consumes the material in which it is located.

  Water animals have a shorter life than terrestrial creatures, not strictly because they are humid, but because they are watery, and watery moisture is easily [467a1] destroyed, since it is cold and readily congealed. For the same reason bloodless animals perish readily unless protected by great size, for there is neither fatness nor sweetness about them. In animals fat is sweet, and hence bees are longer-lived than other animals of larger size. [5]

  6 · It is amongst the plants that we find the longest life—more than among the animals, for, in the first place, they are less watery and hence less easily frozen. Further they have an oiliness and a viscosity which makes them retain their moisture in a form not easily dried up, even though they are dry and earthy.

  But we must discover the reason why trees are of an enduring constitution, for [10] it is peculiar to them and is not found in any animals except the insects.

  Plants continually renew themselves and hence last for a long time. New shoots continually come and the others grow old, and with the roots the same thing happens. But both processes do not occur together. Rather it happens that at one [15] time the trunk and the branches alone die and new ones grow up beside them, and it is only when this has taken place that the fresh roots spring from the surviving part. Thus it continues, one part dying and the other growing, and hence also it lives a long time.

  There is a similarity, as has been already said, between plants and insects, for they live, though divided, and two or more may be derived from a single one. [20] Insects, however, though managing to live, are not able to do so long, for they do not possess organs; nor can the principle resident in each of the separated parts create organs. In the case of a plant, however, it can do so; every part of a plant contains potentially both root and stem. Hence it is from this source that issues that continued growth when one part is renewed and the other grows old; it is practically [25] a case of longevity. The taking of cuttings furnishes a similar instance; for we might say that, in a way, when we take a cutting the same thing happens; the shoot cut off is part of the plant. Thus in taking cuttings this perpetuation of life occurs though their connexion with the plant is severed, but in the former case it is the continuity that is operative. The reason is that the life principle potentially belonging to them is present in every part.

  [30] Identical phenomena are found both in plants and in animals. For in animals the males are, in general, the longer-lived. They have their upper parts larger than the lower (the male is more of the dwarf type of build than the female), and it is in the upper part that warmth resides, in the lower cold. In plants also those with great [467b1] heads are longer-lived, and such are those that are not annual but of the tree-type, for the roots are the head and upper part of a plant, and among the annuals growth occurs in the direction of their lower parts and the fruit.

  These matters however will be specially investigated in the work On Plants. [5] But this is our account of the reasons for the duration of life and for short life in animals. It remains for us to discuss youth and age, and life and death. To come to a definite understanding about these matters would complete our course of study on animals.

  **TEXT: W. D. Ross, Aristotle: Parva Naturalia, Clarendon Press, Oxford, 1955

  1Ross excises this paragraph.

  ON YOUTH, OLD AGE, LIFE AND DEATH, AND RESPIRATION**

  G. R. T. Ross

  1 · We must now treat of youth and old age and life and death. We must [10] probably also at the same time state the causes of respiration as well, since in some cases living and the reverse depend on this.

  We have elsewhere given an account of the soul, and while it is clear that its substance cannot be corporeal, yet manifestly it must exist in some bodily part [15] which must be one of those possessing control over the members. Let us for the present set aside the other parts or faculties of the soul (whichever of the two be the correct name). But as to being what is called an animal and a living thing, we find that in all beings endowed with both characteristics (viz. being an animal and being alive) there must be a single identical part in virtue of which they live and are called [20] animals; for an animal qua animal cannot avoid being alive. But a thing need not, though alive, be animal; for plants live without having sensation, and it is by sensation that we distinguish animal from what is not animal. [25]

  This part, then, must be one and the same in number and yet multiple and disparate in being; for being animal and living are not identical. Since then the organs of special sensation have one common organ in which the senses when functioning must meet, and this must be situated midway between what is called before and behind (we call ‘before’ the direction from which sensation comes, [30] ‘behind’ the opposite), further, since in all living things the body is divided into upper and lower (they all have upper and lower parts, so that this is true of plants as well), clearly the nutritive principle must be situated midway between these regions. That part where food enters we call upper, considering it by itself and not [468a1] relatively to the surrounding universe, while downward is that part by which the primary excrement is discharged.

  Plants are the reverse of animals in this respect. To man in particular among the animals, on account of his erect stature, belongs the characteristic of having his [5] upper parts pointing upwards in the sense in which that applies to the universe, while in the others these are in an intermediate position. But in plants, owing to their being stationary and drawing their sustenance from the ground, the upper part [10] must always be down; for there is a correspondence between the roots in a plant and what is called the mouth in animals, by means of which they take in their food, some from the earth, some by their own efforts.

  2 · All perfectly formed animals are to be divided into three parts, one that [15] by which food is taken in, one that by which excrement is discharged, and the third the region intermediate between them. In the largest animals this latter is called the chest and in the others something corresponding; in some also it is more distinctly marked off than in others. All those also that are capable of progression have additional members subservient to this purpose, by means of which they bear the [20] whole trunk, to wit legs and feet and whatever parts are possessed of the same powers. Now it is evident both by observation and by inference that the source of the nutritive soul is in the middle of the three parts. For many animals, when either part—the head or the receptacle of the food—is cut off, retain life in that member [25] to which the middle remains attached. This can be seen to occur in many insects, e.g. wasps and bees, and many animals also besides insects can, though divided, continue to live by means of the part connected with nutrition.

  While this member is indeed in actuality single, yet potentially it is multiple, [30] for these animals have a constitution similar to that of plants; plants when cut into sections continue to live, and a number of trees can be derived from one single source. A separate account will be given of the reason why some plants cannot live when divided, while others can be propagated by the taking of cuttings. In this [468b1] respect, however, plants and insects are alike.

  It is true that the nutritive soul, in beings possessing it, while actually single must be potentially plural. And so it is too with the principle of sensation, for [5] evidently the divided segments of these animals have sensation. They are unable, however, to preserve their constitution, as plants can, not possessing the organs on which the continuance of life depends; for some lack the means for seizing, others for receiving their food, and some lack both of these and others too.

  [10] Divisible animals are like a number of animals grown together, but animals of superior construction behave differently because their constitution is a unity of the highest possible kind. Hence some of the orga
ns on division display slight sensitiveness because they retain some psychical susceptibility; the animals continue to move after the vitals have been abstracted: tortoises, for example, do so [15] even after the heart has been removed.

  3 · The same phenomenon is evident both in plants and in animals, and in plants we note it both in their propagation by seed and in grafts and cuttings. Genesis from seeds always starts from the middle. All seeds are bivalvular, and it is [20] from the meeting-place and mid-point of the two parts that both root and stem of growing things emerge; the starting-point is in a central position between them. In the case of grafts and cuttings this is particularly true of the buds; for the bud is in a way the starting-point of the branch, but at the same time it is in a central position. [25] Hence it is either this that is cut off, or into this that the new shoot is inserted, when we wish either a new branch or a new root to spring from it; which proves that the point of origin in growth is intermediate between stem and root.

  Likewise in sanguineous animals the heart is the first organ developed; this is evident from what has been observed in those cases where observation of their growth is possible. Hence in bloodless animals also what corresponds to the heart [30] must develop first. We have already asserted in our treatise on the parts of animals that it is from the heart that the veins issue, and that in sanguineous animals the blood is the final nutriment from which the members are formed. Hence it is clear [469a1] that there is one function in nutrition which the mouth has the faculty of performing, and a different one appertaining to the stomach. But it is the heart that has supreme control, exercising an additional and completing function. Hence in sanguineous animals the source both of the sensitive and the nutritive soul must be [5] in the heart, for the functions relative to nutrition exercised by the other parts are ancillary to the activity of the heart. It is the part of the dominating organ to achieve the final result, as of the physician’s efforts to be directed towards health, and not to be occupied with subordinate offices.

  Certainly, however, all sanguineous animals have the supreme organ of the [10] sense-faculties in the heart, for it is here that we must look for the common sensorium belonging to all the sense-organs. These in two cases, taste and touch, can be clearly seen to extend to the heart, and hence the others also must lead to it, for in it the other organs may possibly initiate changes, whereas with the upper region of [15] the body taste and touch have no connexion. Apart from these considerations, if the life is always located in this part, evidently the principle of sensation must be situated there too, for it is qua animal that a body is said to be a living thing, and it is called animal because endowed with sensation. Elsewhere in other works we have stated the reasons why some of the sense-organs are, as is evident, connected with [20] the heart, while others are situated in the head. (It is this fact that causes some people to think that it is in virtue of the brain that the function of perception belongs to animals.)

  4 · Thus if, on the one hand, we look to the observed facts, what we have said makes it clear that the source of the sensitive soul, together with that connected with growth and nutrition, is situated in this organ and in the central one of the [25] three divisions of the body. But it follows by reason also; for we see that in every case, when several paths are open, Nature always chooses the best. Now if both principles are located in the midst of the substance, the two parts of the body, viz. [30] that which elaborates and that which receives the nutriment in its final form will best perform their appropriate function; for the soul will then be close to each, and the central situation which it will, as such, occupy the position of a dominating power.

  [469b1] Further, that which employs an instrument and the instrument it employs must be distinct both in capacity and, if possible, in location, just as the flute and that which plays it—the hand—are diverse. Thus if animal is defined by the possession of sensitive soul, this principle must in the sanguineous animals be in the [5] heart, and, in the bloodless ones, in the corresponding part of their body. But in animals all the members and the whole body possess some connate natural heat, and hence when alive they are observed to be warm, but when dead and deprived of life [10] they are the opposite. Indeed, the source of this warmth must be in the heart in sanguineous animals, and in the case of bloodless animals in the corresponding organ, for, though all parts of the body by means of their natural heat work upon and concoct the nutriment, the governing organ takes the chief share in this process. Hence, even when the other members become cold, life remains; but when the [15] warmth here is quenched, death always ensues, because the source of heat in all the other members depends on this, and the soul is, as it were, set aglow with fire in this part, which in sanguineous animals is the heart and in the bloodless order the analogous member. Hence, of necessity, life must be simultaneous with the [20] maintenance of heat, and what we call death is its destruction.

  5 · However, it is to be noticed that there are two ways in which fire ceases to exist; it may go out either by exhaustion or by extinction. That which is self-caused we call exhaustion, that due to its opposites extinction. But either of these ways in which fire ceases to be may be brought about by the same cause, for, when there is a [25] deficiency of nutriment and the warmth can obtain no maintenance, the fire fails; and the reason is that the opposite, checking digestion, prevents the fire from being fed. But in other cases the result is exhaustion,—when the heat accumulates excessively owing to lack of respiration and of refrigeration. For the heat, accumulating in great quantity, quickly uses up its nutriment and consumes it all [30] before more is sent up by exhalation. Hence not only is a smaller fire readily put out by a larger one, but of itself the lamp’s flame is consumed when inserted in a large [470a1] blaze, just as is the case with any other combustible. The reason is that the nutriment in the flame is seized by the larger one before fresh fuel can be added, for fire is ever coming into being and flowing like a river, but so speedily as to elude observation.

  [5] Clearly, therefore, if the bodily heat must be conserved (as is necessary if life is to continue), there must be some way of cooling the heat resident in the source of warmth. Take as an illustration what occurs when coals are confined in a brazier. If they are kept covered up continuously by the so-called ‘choker’, they are quickly [10] extinguished, but, if the lid is in rapid alternation lifted up and put on again they remain glowing for a long time. Banking up a fire also keeps it in, for the ashes, being porous, do not prevent the passage of air, and again they enable it to resist extinction by the surrounding air by means of the supply of heat which it possesses. [15] However, we have stated in the Problems the reasons why these operations, namely banking up and covering up a fire, have the opposite effects (in the one case the fire goes out, in the other it continues alive for a considerable time).

  6 · Everything living has soul, and it, as we have said, cannot exist without [20] the presence of natural heat. In plants the natural heat is sufficiently well kept alive by the aid which their nutriment and the surrounding air supply. For the food has a cooling effect when it enters (as it does for men immediately after a meal), whereas abstinence from food produces heat and thirst. The air, if it be motionless, becomes [25] hot, but by the entry of food a motion is set up which lasts until digestion is completed and so cools it. If the surrounding air is excessively cold owing to the time of year, there being severe frost, the force of the heat dwindles; but when there are hot spells and the moisture drawn from the ground cannot produce its cooling [30] effect, the heat comes to an end by exhaustion. Trees suffering at such seasons are said to be blighted or star-stricken. Hence the practice of laying beneath the roots stones of certain species or water in pots, for the purpose of cooling the roots of the [470b1] plants.

  Some animals pass their life in the water, others in the air, and therefore these media furnish the source and means of refrigeration, water in the one case, air in the other. We must proceed—and it will require further application on our part—to give an acc
ount of the way and manner in which this refrigeration occurs. [5]

  7(1) · A few of the earlier natural scientists have spoken of respiration. The reason, however, why it exists in animals they have either not declared or, when they have, their statements are not correct and show a comparative lack of acquaintance with the facts. Moreover they assert that all animals respire—which is untrue. [10] Hence these points must first claim our attention, in order that we may not be thought to make unsubstantiated charges against authors no longer alive.

  First then, it is evident that all animals with lungs breathe, but in some cases breathing animals have a bloodless and spongy lung, and then there is less need for respiration. These animals can remain under water for a time, which relatively to [15] their bodily strength, is considerable. All oviparous animals, e.g. the frog-tribe, have a spongy lung. Also turtles and terrapins can remain for a long time immersed in water; for their lung, containing little blood, has not much heat. Hence, when [20] once it is inflated, it itself, by means of its motion, produces a cooling effect and enables the animal to remain immersed for a long time. Suffocation, however, always ensues if the animal is forced to hold its breath for too long a time, for none of this class take in water in the way fishes do. On the other hand, animals which have the lung charged with blood have greater need of respiration on account of the [25] amount of their heat, while none at all of the others which do not possess lungs, breathes.

  8(2) · Democritus of Abdera and certain others who have treated of respiration, while saying nothing definite about the lungless animals, nevertheless seem to speak as if all breathed. But Anaxagoras and Diogenes both maintain that [30] all breathe, and state the manner in which fishes and oysters respire. Anaxagoras says that when fishes discharge water through their gills, air is formed in the mouth, [471a1] for there can be no vacuum, and that it is by drawing in this that they respire. Diogenes’ statement is that, when they discharge water through their gills, they suck the air out of the water surrounding the mouth by means of the vacuum formed [5] in the mouth, for he believes there is air in the water.