by Aristotle
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