Various Works

  their gills or some similar organ. Voice is the sound made by an

  animal, and that with a special organ. As we saw, everything that

  makes a sound does so by the impact of something (a) against something

  else, (b) across a space, (c) filled with air; hence it is only to

  be expected that no animals utter voice except those which take in

  air. Once air is inbreathed, Nature uses it for two different

  purposes, as the tongue is used both for tasting and for articulating;

  in that case of the two functions tasting is necessary for the

  animal's existence (hence it is found more widely distributed),

  while articulate speech is a luxury subserving its possessor's

  well-being; similarly in the former case Nature employs the breath

  both as an indispensable means to the regulation of the inner

  temperature of the living body and also as the matter of articulate

  voice, in the interests of its possessor's well-being. Why its

  former use is indispensable must be discussed elsewhere.

  The organ of respiration is the windpipe, and the organ to which

  this is related as means to end is the lungs. The latter is the part

  of the body by which the temperature of land animals is raised above

  that of all others. But what primarily requires the air drawn in by

  respiration is not only this but the region surrounding the heart.

  That is why when animals breathe the air must penetrate inwards.

  Voice then is the impact of the inbreathed air against the

  'windpipe', and the agent that produces the impact is the soul

  resident in these parts of the body. Not every sound, as we said, made

  by an animal is voice (even with the tongue we may merely make a sound

  which is not voice, or without the tongue as in coughing); what

  produces the impact must have soul in it and must be accompanied by an

  act of imagination, for voice is a sound with a meaning, and is not

  merely the result of any impact of the breath as in coughing; in voice

  the breath in the windpipe is used as an instrument to knock with

  against the walls of the windpipe. This is confirmed by our

  inability to speak when we are breathing either out or in-we can

  only do so by holding our breath; we make the movements with the

  breath so checked. It is clear also why fish are voiceless; they

  have no windpipe. And they have no windpipe because they do not

  breathe or take in air. Why they do not is a question belonging to

  another inquiry.

  9

  Smell and its object are much less easy to determine than what we

  have hitherto discussed; the distinguishing characteristic of the

  object of smell is less obvious than those of sound or colour. The

  ground of this is that our power of smell is less discriminating and

  in general inferior to that of many species of animals; men have a

  poor sense of smell and our apprehension of its proper objects is

  inseparably bound up with and so confused by pleasure and pain,

  which shows that in us the organ is inaccurate. It is probable that

  there is a parallel failure in the perception of colour by animals

  that have hard eyes: probably they discriminate differences of

  colour only by the presence or absence of what excites fear, and

  that it is thus that human beings distinguish smells. It seems that

  there is an analogy between smell and taste, and that the species of

  tastes run parallel to those of smells-the only difference being

  that our sense of taste is more discriminating than our sense of

  smell, because the former is a modification of touch, which reaches in

  man the maximum of discriminative accuracy. While in respect of all

  the other senses we fall below many species of animals, in respect

  of touch we far excel all other species in exactness of

  discrimination. That is why man is the most intelligent of all

  animals. This is confirmed by the fact that it is to differences in

  the organ of touch and to nothing else that the differences between

  man and man in respect of natural endowment are due; men whose flesh

  is hard are ill-endowed by nature, men whose flesh is soft,

  wellendowed.

  As flavours may be divided into (a) sweet, (b) bitter, so with

  smells. In some things the flavour and the smell have the same

  quality, i.e. both are sweet or both bitter, in others they diverge.

  Similarly a smell, like a flavour, may be pungent, astringent, acid,

  or succulent. But, as we said, because smells are much less easy to

  discriminate than flavours, the names of these varieties are applied

  to smells only metaphorically; for example 'sweet' is extended from

  the taste to the smell of saffron or honey, 'pungent' to that of

  thyme, and so on.

  In the same sense in which hearing has for its object both the

  audible and the inaudible, sight both the visible and the invisible,

  smell has for its object both the odorous and the inodorous.

  'Inodorous' may be either (a) what has no smell at all, or (b) what

  has a small or feeble smell. The same ambiguity lurks in the word

  'tasteless'.

  Smelling, like the operation of the senses previously examined,

  takes place through a medium, i.e. through air or water-I add water,

  because water-animals too (both sanguineous and non-sanguineous)

  seem to smell just as much as land-animals; at any rate some of them

  make directly for their food from a distance if it has any scent. That

  is why the following facts constitute a problem for us. All animals

  smell in the same way, but man smells only when he inhales; if he

  exhales or holds his breath, he ceases to smell, no difference being

  made whether the odorous object is distant or near, or even placed

  inside the nose and actually on the wall of the nostril; it is a

  disability common to all the senses not to perceive what is in

  immediate contact with the organ of sense, but our failure to

  apprehend what is odorous without the help of inhalation is peculiar

  (the fact is obvious on making the experiment). Now since bloodless

  animals do not breathe, they must, it might be argued, have some novel

  sense not reckoned among the usual five. Our reply must be that this

  is impossible, since it is scent that is perceived; a sense that

  apprehends what is odorous and what has a good or bad odour cannot

  be anything but smell. Further, they are observed to be

  deleteriously effected by the same strong odours as man is, e.g.

  bitumen, sulphur, and the like. These animals must be able to smell

  without being able to breathe. The probable explanation is that in man

  the organ of smell has a certain superiority over that in all other

  animals just as his eyes have over those of hard-eyed animals. Man's

  eyes have in the eyelids a kind of shelter or envelope, which must

  be shifted or drawn back in order that we may see, while hardeyed

  animals have nothing of the kind, but at once see whatever presents

  itself in the transparent medium. Similarly in certain species of

  animals the organ of smell is like the eye of hard-eyed animals,

  uncurtained, while in others which take in air it probably has a

  curtain over it, which is drawn back in inhalatio
n, owing to the

  dilating of the veins or pores. That explains also why such animals

  cannot smell under water; to smell they must first inhale, and that

  they cannot do under water.

  Smells come from what is dry as flavours from what is moist.

  Consequently the organ of smell is potentially dry.

  10

  What can be tasted is always something that can be touched, and just

  for that reason it cannot be perceived through an interposed foreign

  body, for touch means the absence of any intervening body. Further,

  the flavoured and tasteable body is suspended in a liquid matter,

  and this is tangible. Hence, if we lived in water, we should

  perceive a sweet object introduced into the water, but the water would

  not be the medium through which we perceived; our perception would

  be due to the solution of the sweet substance in what we imbibed, just

  as if it were mixed with some drink. There is no parallel here to

  the perception of colour, which is due neither to any blending of

  anything with anything, nor to any efflux of anything from anything.

  In the case of taste, there is nothing corresponding to the medium

  in the case of the senses previously discussed; but as the object of

  sight is colour, so the object of taste is flavour. But nothing

  excites a perception of flavour without the help of liquid; what

  acts upon the sense of taste must be either actually or potentially

  liquid like what is saline; it must be both (a) itself easily

  dissolved, and (b) capable of dissolving along with itself the tongue.

  Taste apprehends both (a) what has taste and (b) what has no taste, if

  we mean by (b) what has only a slight or feeble flavour or what

  tends to destroy the sense of taste. In this it is exactly parallel to

  sight, which apprehends both what is visible and what is invisible

  (for darkness is invisible and yet is discriminated by sight; so is,

  in a different way, what is over brilliant), and to hearing, which

  apprehends both sound and silence, of which the one is audible and the

  other inaudible, and also over-loud sound. This corresponds in the

  case of hearing to over-bright light in the case of sight. As a

  faint sound is 'inaudible', so in a sense is a loud or violent

  sound. The word 'invisible' and similar privative terms cover not only

  (a) what is simply without some power, but also (b) what is adapted by

  nature to have it but has not it or has it only in a very low

  degree, as when we say that a species of swallow is 'footless' or that

  a variety of fruit is 'stoneless'. So too taste has as its object both

  what can be tasted and the tasteless-the latter in the sense of what

  has little flavour or a bad flavour or one destructive of taste. The

  difference between what is tasteless and what is not seems to rest

  ultimately on that between what is drinkable and what is undrinkable

  both are tasteable, but the latter is bad and tends to destroy

  taste, while the former is the normal stimulus of taste. What is

  drinkable is the common object of both touch and taste.

  Since what can be tasted is liquid, the organ for its perception

  cannot be either (a) actually liquid or (b) incapable of becoming

  liquid. Tasting means a being affected by what can be tasted as

  such; hence the organ of taste must be liquefied, and so to start with

  must be non-liquid but capable of liquefaction without loss of its

  distinctive nature. This is confirmed by the fact that the tongue

  cannot taste either when it is too dry or when it is too moist; in the

  latter case what occurs is due to a contact with the pre-existent

  moisture in the tongue itself, when after a foretaste of some strong

  flavour we try to taste another flavour; it is in this way that sick

  persons find everything they taste bitter, viz. because, when they

  taste, their tongues are overflowing with bitter moisture.

  The species of flavour are, as in the case of colour, (a) simple,

  i.e. the two contraries, the sweet and the bitter, (b) secondary, viz.

  (i) on the side of the sweet, the succulent, (ii) on the side of the

  bitter, the saline, (iii) between these come the pungent, the harsh,

  the astringent, and the acid; these pretty well exhaust the

  varieties of flavour. It follows that what has the power of tasting is

  what is potentially of that kind, and that what is tasteable is what

  has the power of making it actually what it itself already is.

  11

  Whatever can be said of what is tangible, can be said of touch,

  and vice versa; if touch is not a single sense but a group of

  senses, there must be several kinds of what is tangible. It is a

  problem whether touch is a single sense or a group of senses. It is

  also a problem, what is the organ of touch; is it or is it not the

  flesh (including what in certain animals is homologous with flesh)? On

  the second view, flesh is 'the medium' of touch, the real organ

  being situated farther inward. The problem arises because the field of

  each sense is according to the accepted view determined as the range

  between a single pair of contraries, white and black for sight,

  acute and grave for hearing, bitter and sweet for taste; but in the

  field of what is tangible we find several such pairs, hot cold, dry

  moist, hard soft, c. This problem finds a partial solution, when it

  is recalled that in the case of the other senses more than one pair of

  contraries are to be met with, e.g. in sound not only acute and

  grave but loud and soft, smooth and rough, c.; there are similar

  contrasts in the field of colour. Nevertheless we are unable clearly

  to detect in the case of touch what the single subject is which

  underlies the contrasted qualities and corresponds to sound in the

  case of hearing.

  To the question whether the organ of touch lies inward or not

  (i.e. whether we need look any farther than the flesh), no

  indication in favour of the second answer can be drawn from the fact

  that if the object comes into contact with the flesh it is at once

  perceived. For even under present conditions if the experiment is made

  of making a web and stretching it tight over the flesh, as soon as

  this web is touched the sensation is reported in the same manner as

  before, yet it is clear that the or is gan is not in this membrane. If

  the membrane could be grown on to the flesh, the report would travel

  still quicker. The flesh plays in touch very much the same part as

  would be played in the other senses by an air-envelope growing round

  our body; had we such an envelope attached to us we should have

  supposed that it was by a single organ that we perceived sounds,

  colours, and smells, and we should have taken sight, hearing, and

  smell to be a single sense. But as it is, because that through which

  the different movements are transmitted is not naturally attached to

  our bodies, the difference of the various sense-organs is too plain to

  miss. But in the case of touch the obscurity remains.

  There must be such a naturally attached 'medium' as flesh, for no

  living body could be constructed of air or water; it must be something

  soli
d. Consequently it must be composed of earth along with these,

  which is just what flesh and its analogue in animals which have no

  true flesh tend to be. Hence of necessity the medium through which are

  transmitted the manifoldly contrasted tactual qualities must be a body

  naturally attached to the organism. That they are manifold is clear

  when we consider touching with the tongue; we apprehend at the

  tongue all tangible qualities as well as flavour. Suppose all the rest

  of our flesh was, like the tongue, sensitive to flavour, we should

  have identified the sense of taste and the sense of touch; what

  saves us from this identification is the fact that touch and taste are

  not always found together in the same part of the body. The

  following problem might be raised. Let us assume that every body has

  depth, i.e. has three dimensions, and that if two bodies have a

  third body between them they cannot be in contact with one another;

  let us remember that what is liquid is a body and must be or contain

  water, and that if two bodies touch one another under water, their

  touching surfaces cannot be dry, but must have water between, viz. the

  water which wets their bounding surfaces; from all this it follows

  that in water two bodies cannot be in contact with one another. The

  same holds of two bodies in air-air being to bodies in air precisely

  what water is to bodies in water-but the facts are not so evident to

  our observation, because we live in air, just as animals that live

  in water would not notice that the things which touch one another in

  water have wet surfaces. The problem, then, is: does the perception of

  all objects of sense take place in the same way, or does it not,

  e.g. taste and touch requiring contact (as they are commonly thought

  to do), while all other senses perceive over a distance? The

  distinction is unsound; we perceive what is hard or soft, as well as

  the objects of hearing, sight, and smell, through a 'medium', only

  that the latter are perceived over a greater distance than the former;

  that is why the facts escape our notice. For we do perceive everything

  through a medium; but in these cases the fact escapes us. Yet, to