Aristotle

by Various Works [lit]

  softness of voice) except by the large and small amount of the air

  put in motion? If then height and depth are to be decided in

  accordance with the distinction postulated, the result will be that

  the same animals will be deep-and loud-voiced, and the same will be

  high-and not loud-voiced; but this is false.

  The reason of the difficulty is that the words 'great' and

  'small', 'much' and 'little' are used sometimes absolutely,

  sometimes relatively to one another. Whether an animal has a great

  (or loud) voice depends on the air which is moved being much

  absolutely, whether it has a small voice depends on its being little

  absolutely; but whether they have a deep or high voice depends on

  their being thus differentiated in relation to one another. For if

  that which is moved surpass the strength of that which moves it, the

  air that is sent forth must go slowly; if the opposite, quickly. The

  strong, then, on account of their strength, sometimes move much air

  and make the movement slow, sometimes, having complete command over

  it, make the movement swift. On the same principle the weak either

  move too much air for their strength and so make the movement slow, or

  if they make it swift move but little because of their weakness.

  These, then, are the reasons of these contrarieties, that neither

  are all young animals high-voiced nor all deep-voiced, nor are all the

  older, nor yet are the two sexes thus opposed, and again that not only

  the sick speak in a high voice but also those in good bodily

  condition, and, further, that as men verge on old age they become

  higher-voiced, though this age is opposite to that of youth.

  Most young animals, then, and most females set but little air in

  motion because of their want of power, and are consequently

  high-voiced, for a little air is carried along quickly, and in the

  voice what is quick is high. But in calves and cows, in the one case

  because of their age, in the other because of their female nature, the

  part by which they set the air in motion is not strong; at the same

  time they set a great quantity in motion and so are deep-voiced; for

  that which is borne along slowly is heavy, and much air is borne along

  slowly. And these animals set much in movement whereas the others

  set but little, because the vessel through which the breath is first

  borne has in them a large opening and necessarily sets much air in

  motion, whereas in the rest the air is better dispensed. As their

  age advances this part which moves the air gains more strength in each

  animal, so that they change into the opposite condition, the

  high-voiced becoming deeper-voiced than they were, and the deep-voiced

  higher-voiced, which is why bulls have a higher voice than calves

  and cows. Now the strength of all animals is in their sinews, and so

  those in the prime of life are stronger, the young being weaker in the

  joints and sinews; moreover, in the young they are not yet tense,

  and in those now growing old the tension relaxes, wherefore both these

  ages are weak and powerless for movement. And bulls are particularly

  sinewy, even their hearts, and therefore that part by which they set

  the air in motion is in a tense state, like a sinewy string

  stretched tight. (That the heart of bulls is of such a nature is

  shown by the fact that a bone is actually found in some of them, and

  bones are naturally connected with sinew.)

  All animals when castrated change to the female character, and utter

  a voice like that of the females because the sinewy strength in the

  principle of the voice is relaxed. This relaxation is just as if one

  should stretch a string and make it taut by hanging some weight on

  to it, as women do who weave at the loom, for they stretch the warp by

  attaching to it what are called 'laiai'. For in this way are the

  testes attached to the seminal passages, and these again to the

  blood-vessel which takes its origin in the heart near the organ

  which sets the voice in motion. Hence as the seminal passages change

  towards the age at which they are now able to secrete the semen,

  this part also changes along with them. As this changes, the voice

  again changes, more indeed in males, but the same thing happens in

  females too, only not so plainly, the result being what some call

  'bleating' when the voice is uneven. After this it settles into the

  deep or high voice of the succeeding time of life. If the testes are

  removed the tension of the passages relaxes, as when the weight is

  taken off the string or the warp; as this relaxes, the organ which

  moves the voice is loosened in the same proportion. This, then, is the

  reason why the voice and the form generally changes to the female

  character in castrated animals; it is because the principle is relaxed

  upon which depends the tension of the body; not that, as some suppose,

  the testes are themselves a ganglion of many principles, but small

  changes are the causes of great ones, not per se but when it happens

  that a principle changes with them. For the principles, though small

  in size, are great in potency; this, indeed, is what is meant by a

  principle, that it is itself the cause of many things without anything

  else being higher than it for it to depend upon.

  The heat or cold also of their habitat contributes to make some

  animals of such a character as to be deep-voiced, and others

  high-voiced. For hot breath being thick causes depth, cold breath

  being thin the opposite. This is clear also in pipe-playing, for if

  the breath of the performer is hotter, that is to say if it is

  expelled as by a groan, the note is deeper.

  The cause of roughness and smoothness in the voice, and of all

  similar inequality, is that the part or organ through which the

  voice is conveyed is rough or smooth or generally even or uneven. This

  is plain when there is any moisture about the trachea or when it is

  roughened by any affection, for then the voice also becomes uneven.

  Flexibility depends on the softness or hardness of the organ, for

  what is soft can be regulated and assume any form, while what is

  hard cannot; thus the soft organ can utter a loud or a small note, and

  accordingly a high or a deep one, since it easily regulates the

  breath, becoming itself easily great or small. But hardness cannot

  be regulated.

  Let this be enough on all those points concerning the voice which

  have not been previously discussed in the treatise on sensation and in

  that on the soul.

  8

  With regard to the teeth it has been stated previously that they

  do not exist for a single purpose nor for the same purpose in all

  animals, but in some for nutrition only, in others also for fighting

  and for vocal speech. We must, however, consider it not alien to the

  discussion of generation and development to inquire into the reason

  why the front teeth are formed first and the grinders later, and why

  the latter are not shed but the former are shed and grow again.

  Democritus has spoken of these questions but not well, for he

  assigns the cause too generally withou
t investigating the facts in all

  cases. He says that the early teeth are shed because they are formed

  in animals too early, for it is when animals are practically in

  their prime that they grow according to Nature, and suckling is the

  cause he assigns for their being found too early. Yet the pig also

  suckles but does not shed its teeth, and, further, all the animals

  with carnivorous dentition suckle, but some of them do not shed any

  teeth except the canines, e.g. lions. This mistake, then, was due to

  his speaking generally without examining what happens in all cases;

  but this is what we to do, for any one who makes any general statement

  must speak of all the particular cases.

  Now we assume, basing our assumption upon what we see, that Nature

  never fails nor does anything in vain so far as is possible in each

  case. And it is necessary, if an animal is to obtain food after the

  time of taking milk is over, that it should have instruments for the

  treatment of the food. If, then, as Democritus says, this happened

  about the time of reaching maturity, Nature would fail in something

  possible for her to do. And, besides, the operation of Nature would be

  contrary to Nature, for what is done by violence is contrary to

  Nature, and it is by violence that he says the formation of the

  first teeth is brought about. That this view then is not true is plain

  from these and other similar considerations.

  Now these teeth are developed before the flat teeth, in the first

  place because their function is earlier (for dividing comes before

  crushing, and the flat teeth are for crushing, the others for

  dividing), in the second place because the smaller is naturally

  developed quicker than the larger, even if both start together, and

  these teeth are smaller in size than the grinders, because the bone of

  the jaw is flat in that part but narrow towards the mouth. From the

  greater part, therefore, must flow more nutriment to form the teeth,

  and from the narrower part less.

  The act of sucking in itself contributes nothing to the formation of

  the teeth, but the heat of the milk makes them appear more quickly.

  A proof of this is that even in suckling animals those young which

  enjoy hotter milk grow their teeth quicker, heat being conducive to

  growth.

  They are shed, after they have been formed, partly because it is

  better so (for what is sharp is soon blunted, so that a fresh relay

  is needed for the work, whereas the flat teeth cannot be blunted but

  are only smoothed in time by wearing down), partly from necessity

  because, while the roots of the grinders are fixed where the jaw is

  flat and the bone strong, those of the front teeth are in a thin part,

  so that they are weak and easily moved. They grow again because they

  are shed while the bone is still growing and the animal is still young

  enough to grow teeth. A proof of this is that even the flat teeth grow

  for a long time, the last of them cutting the gum at about twenty

  years of age; indeed in some cases the last teeth have been grown in

  quite old age. This is because there is much nutriment in the broad

  part of the bones, whereas the front part being thin soon reaches

  perfection and no residual matter is found in it, the nutriment

  being consumed in its own growth.

  Democritus, however, neglecting the final cause, reduces to

  necessity all the operations of Nature. Now they are necessary, it

  is true, but yet they are for a final cause and for the sake of what

  is best in each case. Thus nothing prevents the teeth from being

  formed and being shed in this way; but it is not on account of these

  causes but on account of the end (or final cause); these are

  causes only in the sense of being the moving and efficient instruments

  and the material. So it is reasonable that Nature should perform

  most of her operations using breath as an instrument, for as some

  instruments serve many uses in the arts, e.g. the hammer and anvil

  in the smith's art, so does breath in the living things formed by

  Nature. But to say that necessity is the only cause is much as if we

  should think that the water has been drawn off from a dropsical

  patient on account of the lancet, not on account of health, for the

  sake of which the lancet made the incision.

  We have thus spoken of the teeth, saying why some are shed and

  grow again, and others not, and generally for what cause they are

  formed. And we have spoken of the other affections of the parts

  which are found to occur not for any final end but of necessity and on

  account of the motive or efficient cause.

  -THE END-

  .

  350 BC

  ON THE MOTION OF ANIMALS

  by Aristotle

  translated by A. S. L. Farquharson

  1

  ELSEWHERE we have investigated in detail the movement of animals

  after their various kinds, the differences between them, and the

  reasons for their particular characters (for some animals fly, some

  swim, some walk, others move in various other ways); there remains

  an investigation of the common ground of any sort of animal movement

  whatsoever.

  Now we have already determined (when we were discussing whether

  eternal motion exists or not, and its definition, if it does exist)

  that the origin of all other motions is that which moves itself, and

  that the origin of this is the immovable, and that the prime mover

  must of necessity be immovable. And we must grasp this not only

  generally in theory, but also by reference to individuals in the world

  of sense, for with these in view we seek general theories, and with

  these we believe that general theories ought to harmonize. Now in

  the world of sense too it is plainly impossible for movement to be

  initiated if there is nothing at rest, and before all else in our

  present subject- animal life. For if one of the parts of an animal

  be moved, another must be at rest, and this is the purpose of their

  joints; animals use joints like a centre, and the whole member, in

  which the joint is, becomes both one and two, both straight and

  bent, changing potentially and actually by reason of the joint. And

  when it is bending and being moved one of the points in the joint is

  moved and one is at rest, just as if the points A and D of a

  diameter were at rest, and B were moved, and DAC were generated.

  However, in the geometrical illustration, the centre is held to be

  altogether indivisible (for in mathematics motion is a fiction, as the

  phrase goes, no mathematical entity being really moved), whereas in

  the case of joints the centres become now one potentially and

  divided actually, and now one actually and divided potentially. But

  still the origin of movement, qua origin, always remains at rest

  when the lower part of a limb is moved; for example, the elbow

  joint, when the forearm is moved, and the shoulder, when the whole

  arm; the knee when the tibia is moved, and the hip when the whole leg.

  Accordingly it is plain that each animal as a whole must have within

  itself a point at rest, whence will be the ori
gin of that which is

  moved, and supporting itself upon which it will be moved both as a

  complete whole and in its members.

  2

  But the point of rest in the animal is still quite ineffectual

  unless there be something without which is absolutely at rest and

  immovable. Now it is worth while to pause and consider what has been

  said, for it involves a speculation which extends beyond animals

  even to the motion and march of the universe. For just as there must

  be something immovable within the animal, if it is to be moved, so

  even more must there be without it something immovable, by

  supporting itself upon which that which is moved moves. For were

  that something always to give way (as it does for mice walking in

  grain or persons walking in sand) advance would be impossible, and

  neither would there be any walking unless the ground were to remain

  still, nor any flying or swimming were not the air and the sea to

  resist. And this which resists must needs be different from what is

  moved, the whole of it from the whole of that, and what is thus

  immovable must be no part of what is moved; otherwise there will be no

  movement. Evidence of this lies in the problem why it is that a man

  easily moves a boat from outside, if he push with a pole, putting it

  against the mast or some other part, but if he tried to do this when

  in the boat itself he would never move it, no not giant Tityus himself

  nor Boreas blowing from inside the ship, if he really were blowing

  in the way painters represent him; for they paint him sending the

  breath out from the boat. For whether one blew gently or so stoutly as

  to make a very great wind, and whether what were thrown or pushed were

  wind or something else, it is necessary in the first place to be

  supported upon one of one's own members which is at rest and so to

  push, and in the second place for this member, either itself, or

  that of which it is a part, to remain at rest, fixing itself against