to fire, since two bodies cannot possibly coexist in
one and the same body.
Light seems to be the opposite to darkness ; and
as darkness is the absence of a particular state of the
diaphanous, it is evident that the presence of that
state must be light.
Thus Empedocles, or whoever else may have held
the same opinion, was wrong in supposing that light
was transported and manifested, without our con-
sciousness, between the Earth and surrounding space;
for the opinion is opposed as well to sound conclusion
CH. VII.] VITAL PRINCIPLE. 95
as to observation of the phenomenon. If the interval
were small, the fact might, indeed, escape us; but,
extended as it is from the East to the West, the pos-
tulate is too extravagant to be admitted.
Now that which is without colour is receptive of
colour, as that which is without sound is receptive of
sound; and that which is without colour is the dia-
phanous and the invisible or scarcely visible, such as
darkness seems to be. Such too is the diaphanous ;
but then it is the diaphanous, not in potentiality but,
in reality; for the same nature is sometimes darkness
and sometimes light. But all objects are not visible
in light, as there are some of which the peculiar
colour only of each is visible; for some, not visible
in light, produce sensation in the dark, as certain
fiery brilliant appearances (which have no special
appellation,) which emanate from fungi, horn, scales
and eyes of fishes, but the peculiar colour is not seen
of any one of those objects. It is foreign to our present
purpose to explain how such objects become visible ;
but this much is manifest, that it is colour which is
visible in light. Therefore, without light colour is
not visible; for it is an essential property of colour to
be motive of the diaphanous in activity, and the
reality of the diaphanous is light. As proof of this,
if any coloured object be placed over the sight, the
object will not be seen, and yet there is colour, which
is motive of the diaphanous, the air, that is, and, by
96 ARISTOTLE ON THE [BK. II.
its being continuous between the object and the sense,
it is able to give motion to the visual organ. Thus.
Democritus was wrong in thinking that if the medium
were a void, vision would be so accurate as to render
an ant visible in the sky. The opinion, in fact, in-
volves an impossibility; for vision is produced by
some kind of impression upon the visual organ, and
as this cannot possibly be effected by the colour which
is visible, there remains only that it must be by the
medium, and thus a medium there must be ; so that
if there were a void, vision would be, not to say in-
accurate but, altogether precluded.
It has thus then been said why colour must be
visible in the light ; but fire is visible both in dark-
ness and in light, and necessarily so, since it is by fire
that the diaphanous becomes diaphanous. The same
reasoning holds good for sound and for odour, as
nothing sonorous or odorous can produce sensation
when in immediate contact with the sentient organ ;
but by odour or sound the medium is set in motion,
and by it the organ is moved. Thus, when any thing
sonorous or odorous is placed immediately upon the
sentient organ, no sensation is given out ; and this is
the case with the sense of Touch, although less evi-
dently so ; but the cause of this shall be explained
hereafter. The air is the medium for sounds, while
that for odour has no special appellation, for there is
a particular impression common to air and water ; and
CH. VII.] VITAL PRINCIPLE. 97
what the diaphanous is to colour that which is in
those elements is to odorous bodies, as aquatic ani-
mals appear to be sensible of odours. But neither
man nor animals which breathe can smell without
inspiring; and the cause of this shall be spoken
of hereafter.
PKELTJDE TO CHAPTER VIII.
THIS chapter is upon sound and hearing ; and as these
subjects had been but desultorily alluded to in the
other works, they are treated of at some length on
this occasion. It opens with the distinction of
bodies into sonorous and insonorous, and after tracing
the analogy between the acute and grave, and the
sharp and blunt (of touch), it passes by a rapid
transition to the voice, which is dwelt upon at some
length. The term evtpycta, which had been used in
place of evT\-^fta, to express the active as opposed
to the potential or negative state of the diaphaneity,
is again employed here to signify the analogous and
contrasting quality of sound. The distinction between
the terms is not very apparent now, although this
may not have been the case then ; for the evepyeta
may have conveyed the idea of action in the transi-
tion from potentiality, and so have been more
expressive of actual, as opposed to virtual light or
sound. Thus, if sound be a quality or condition, it
PRELUDE TO CHAP. VIII. 99
may be active, and it may be only virtual or faint ;
but although to us inaudible, it is not to be supposed
that silence any more than darkness is ever absolute ;
so that the text has limited the range of sound too
absolutely by the activity of the sense. Aristotle 1
assigned, as has been said, a high privilege to this
sense, because through it instruction is orally con-
veyed, and thus the blind from birth are more intel-
ligent ((ppovtutorepot), he observes, than "the deaf
and dumb;" but the argument would have been
more correct had the second term been omitted, as
individuals are of necessity dumb when hearing is
quite shut out. The phraseology, however, is still
sanctioned in common parlance.
1 De Sensu et sensili i. 1 1.
72
CHAPTEE VIII.
LET us now proceed to determine the nature of sound
and hearing. Sound is double one actual and an-
other potential ; for we say that some substances, such
as sponge and wool, are without sound ; and that
others, as brass, and bodies which are hard and
smooth, have sound, because such objects are able to
sound ; are able, that is, to create actual sound by the
action of the medium between the object and the
hearing. Sound of the actual kind is the invariable
result of something in relation to something and in
something ; for its producing cause is percussion. It
is impossible, therefore, that sound should be pro-
duced when there is only one substance, as that which
percusses must be distinct from that which is per-
cussed; so that the sonorous object sounds by its
relation to another object. But there can be no per-
cussion without movement, and sound is not produced
by the percussion of any kind of substance, as we
have said, (since wool, however percussed, does not,
while brass and smooth and hollow bodies brass
because it is smooth do give out sound,) and hollow
bodies create, by reflexion, many percussions after the
CH. VIII.] ARISTOTLE ON THE VITAL PRINCIPLE. 101
first, owing to the medium within them having been
set in motion and being unable to make its escape.
Sound is audible in air, and so it is in water, although
less distinctly ; but neither air nor water is the efficient
cause of sound, as for it there must be percussion of
solid bodies against each other and against the air,
and this is effected whenever the air, having been
percussed, remains, is not, that is, dispersed. Thus,
if the air be struck sharply and forcibly it gives out
sound ; for the motion of that which percusses should
anticipate the dispersion of the air, as if any one were
striking a rapidly moving heap or cloud of sand.
An echo is produced whenever the external air has
been more than once repelled by the air contained
within a vessel, by the sides of which that air is pre-
cluded from being dispersed, just as a ball rebounds.
It seems as though an echo ought to be a constant
occurrence, although it may not be audible, since that
happens to sound which happens to light, and light is
continually undergoing reflexion (for, otherwise, as
light could not be everywhere, darkness would pre-
vail beyond the spot illumined by the sun), but yet it
is not everywhere reflected, as it is from water or
brass or any other smooth body, so as to form a
shadow whereby we are able to distinguish the light
itself.
A Void is rightly said to be the sovereign cause
of hearing; for the air seems to be a void, and the
102 ARISTOTLE ON THE [BK. II.
air, when moving continuously and as one body, is
creative of hearing. But, owing to its being very dif-
fluent, it gives out no sound, unless that which is
percussed be smooth ; when this, however, is the case,
the air becomes simultaneously one over the surface,
as the surface of every smooth body is one. Every
sonorous body is so constituted as to set in motion the
air which, by continuity, is one up to the hearing,
and the hearing is naturally connected with the air ;
and owing to sound being in the air, the air which is
without sets in motion that which is within. An ani-
mal, therefore, does not hear everywhere, neither does
the air penetrate everywhere; for the part to be set
in motion is a living part, and does not everywhere
contain air. The air itself, owing to its ready diffusi-
bility, is without sound ; but, when precluded from
being dispersed, its motion is productive of sound.
The air which is within the ears has been so immured
as to be immovable ; and this in order that the sense
may perceive accurately all variations of its move-
ment. It is for these reasons that we are able to hear
when in the water, as the water cannot gain access to
the congenital air, or pass into the ear through the
convolutions ; when, however, this does happen, there
is no hearing, any more than there is when the mem-
brane of the ear, which is to it what the skin over the
pupil is to the eye, is diseased. But proof is afforded
whether the hearing is perfect or not, in that the ear
CH. VIII.] VITAL PRINCIPLE. 103
is constantly giving out sound, just as a horn does ;
for the air within the ears is continually moving in
some peculiar manner, and yet sound is foreign to
that air and forms no part of its properties. It is on
this account, however, that we speak of hearing by a
void and something resonant, because we hear by the
part which contains the air confined within it.
But is it that which percusses, or that which is
percussed, which gives out sound ? Or do both con-
tribute to its production, each in its own way? Now,
sound is the motion of something which admits of
being moved after the manner of bodies rebounding
from smooth surfaces, whereon they may have been
impelled. But every kind of body, whether percussing
or percussed, does not, as has been said, give out
sound ; as when a sharp point, for example, strikes a
sharp point, there is no sound ; but in order to pro-
duce sound, that which is percussed must be so
smooth, that the mass of air upon its surface may re-
bound from, and be agitated over it. The distinctions
among sonorous bodies are revealed in the actual
sounds which they give forth; for as without light
colours are not visible, so without sound the acute
and grave are not audible. These terms (acute and
grave) are derived from tangible properties, and em-
ployed, in a metaphorical sense, for sounds; for the
acute moves the hearing quickly and sharply, the
grave moves it slowly and dully ; not, however, that
104 ARISTOTLE ON THE [BK. II.
the acute is quick or the grave slow ; but that such is
the motion of the one from the celerity, and such the
motion of the other from the tardiness of its operation
upon the sense. And there does seem to be an ana-
logy between those sounds and the sharp and blunt,
as perceived by the Touch ; for the sharp pricks, and
the blunt pushes, as it were, because the motion ex-
erted by the one is rapid, by the other tardy ; and it is
in this manner that the terms in question have origi-
nated. Let us here, however, close our observations
upon the nature of sound.
The voice is a sound produced by a living crea-
ture; for nothing inanimate speaks, although there
are objects, such as the flute, lyre, and others, which,
having range of note, harmony, and expression, are
said, from a resemblance between their tones and the
voice, to do so; and the voice does seem to have all
the variations of note possessed by those instruments.
Many creatures have no voice (as all the insan-
guineous, for instance, and some of the sanguineous,
as fishes), which is very understandable, seeing that
sound is a certain motion of the air ; and with respect
to those fishes which are found in the Achelous and
said to speak, they produce sound by their gills, or
other such part. But although the voice is a sound
emanating from a living creature, it does not imply
any kind of sound, or a sound produced by any
kind of part; and as all sound is produced by the
CH. VIII.] VITAL PRINCIPLE. 105
conditions of something which percusses, something
percussed, and a something, that is the air, in
which percussion can be made, it might reasonably
be assumed, that such creatures only as take in air can
have a voice. Now, nature employs simultaneously
the air respired for two functions, just as she employs
the tongue for taste and for speech ; and of these the
former is necessary (and therefore imparted to most
creatures), and the latter, as an organ for interpre-
tation, is for their higher good ; so too does she
employ the breath both as necessary for tempering
the heat within (as shall be explained elsewhere), and
for the production of voice, which is for the welfare
of the individual. The pharynx is the organ of
respiration, for the sake of which is another part, the
lung, and it is owing to this part that quadrupeds
have more heat than other creatures.
It is the place about the heart which first needs
respiration ; and, therefore, it is necessary that the
air, during inspiration, should pass inwards; and
thus the percussion of the air respired by the living
principle in those parts, against the so-called trachea,
constitutes the voice. But every sound produced by
an animal is not voice, as we have said (for it is pos-
sible to produce sound by the tongue, as in coughing),
but in order to constitute the voice, there must be a
percussing living force, and the sound produced must
be expressive of something. The voice is, in fact, a
106 ARISTOTLE ON THE VITAL PRINCIPLE. [BK. II.
sound expressive of something it is not, that is, as
in coughing, a mere sound of the air inspired; and
speech is the percussion, by the living principle, of
the air in the trachea, against the trachea itself. As
proof of which, we are unable to speak when holding
the breath, that is, when we neither inspire nor
expire; for the act of holding the breath sets in
motion the air which is inspired. It is now manifest
why fishes, having no pharynx, are without a voice ;
and they have no pharynx, because they neither
admit the air nor breathe. It is foreign to our present
purpose, however, to inquire into the cause of their
having been thus constituted.
PRELUDE TO CHAPTER IX.
MODERN science confirms Aristotle's judgment concerning
the nature of odour, for it is said "to be a curious
and interesting problem, requiring much more investi-
gation than it has hitherto received ;" and, according
to Cuvier *, " of all the substances which act upon our
senses, those which produce the sensation of smell
are the least known, although their impression has
the liveliest and deepest influence upon our economy."
But the reason assigned in the text for this relative
imperfection of our smell is indefinite and question-
able ; for " although man's nostrils are less compli-
cated than those of any animals save the quadrumana,
he is the only creature whose smell is fine enough to
be affected by unpleasant odours" It may be doubted,
besides, whether any sensation can be, as is implied
in the text, so pure as to be freed from all mental
or corporeal association ; but when man's smell is
1 R&gne Animal, T. i. 73.
108 PRELUDE TO CHAP. IX.
compared with that of birds and beasts of prey, it
may be granted that, within a certain range of impres-
sions, it is relatively duller and coarser than with
them. It is, however, assumed, that sight and smell,
when perfect, have the faculty of perceiving colours,
and odours purely, unassociated, that is, with any
impression grateful or otherwise ; and thus, as man's
smell was held to be imperfect, he was supposed to
be sensible of odours as creatures with hard, that is,
compound eyes are of colours. For such creatures 1
(crustacea, insects and others), having their eyes
uncovered, being without lids that is, see objects
which are at a distance " indistinctly, and as if they
were looking through congenitally attached eye-lids."
1 Hist. An. i. 15. 16.
CHAPTER IX.
IT is less easy to define smell and the odorous object,
than the subjects which have just been treated of, as
the nature of odour is not so clear to us as is that of
either sound or colour ; and the reason of this is, that
our sense of smell is inaccurate, is less delicate, in
fact, than it is in many animals. Thus, man has but
a coarse smell, and is never sensible of any thing
odorous without associating therewith an impression
of something painful or grateful ; and this seems to
indicate an organ imperfectly constituted. It is pro-
bable that colours are perceived by creatures which
have hard eyes in this same manner, and that shades
of colour invariably make upon them an impression of
something to be afraid of or otherwise. The human
race is circumstanced in a like manner with respect
to odours ; and there seems to be an analogy between
taste and kinds of savours, and smell and kinds of
odours, but as taste is a kind of touch, and touch of
all man's senses the most perfect, his taste is more
delicate than his smell. With respect to other senses,
man is far behind many animals, but he is especially
110 ARISTOTLE ON THE [BK. II.
distinguished from them all by the accuracy of his
Touch ; and to this he is indebted for being of all the
most intelligent. As proof of which, individuals of
the human race are according to the constitution of
this sense and nothing else, clever or dull for those
with hard flesh are slow, and those, on the contrary,
with soft flesh are quick of understanding.
As one savour is sweet and another bitter, so it
is with odours ; but some bodies impart an analogous
savour and odour, impart, I mean, a sweet odour and
a sweet savour, while other bodies give out their
contraries. Some odours equally with savours are
termed pungent, sour, and oily, but, as we have
already explained, owing to their not being so dis-
tinguishable by us as savours, odours have derived
their appellations from these, on account of the simi-
larity of the objects from which they both proceed.
Thus, the odour from saffron and honey is called sweet,
that from thyme and other herbs of the kind pungent,
and so for other bodies and odours.
There is a close analogy between the other senses
and the hearing : for as it is sensible of the audible
and the inaudible, so is vision of the visible and invi-
sible, and smell of the odorous and the inodorous,
and by inodorous is meant whatever is either alto-
gether without odour, or has but a very faint odour ;
and a sense analogous to this is attached to the term
insapid.
CH. IX.] VITAL PRINCIPLE. Ill
The smell is perceptive through a medium, such
as air or water, for aquatic animals seem to be sen-
sible of odour ; and so, likewise, are sanguineous and
insanguineous creatures, as well as those which wing
the air. Thus, some of these are to be seen proceeding
from a distance towards food, of which they have been
made sensible by the odour emanating from it. And
hence the difficulty of determining why, if other crea-
tures are sensible of odours in a like manner, man
alone can smell neither when expiring nor when
holding his breath but, only when inspiring ; and
this whether the odorous object be at a distance from
or close to him, or placed immediately within the
nostrils. It is common, it is true, to all the sentient
organs to be insensible to impressions when objects
are placed immediately upon them ; but it is peculiar
to man (as may be proved experimentally), to be
unable to perceive odours without inspiring. So that
as insanguineous creatures do not breathe, they ought
to have some other sense besides those spoken of,
but yet this cannot be, since they do perceive odour ;
for the perception of odour, whether agreeable or
disagreeable, is smell; and as these appear to
be destroyed by the same powerful odours as those
which destroy man (odours, for instance, from pitch,
sulphur, and other like substances), we must con-
clude that they have smell, although they do not
breathe.
112 ARISTOTLE ON THE VITAL PRINCIPLE. [BK. II.
The olfactory organ in man appears to differ from
that in other animals as his eyes differ from those of
creatures in which they are hard ; for man's eyes are
furnished with a rampart, and a kind of sheath in
lids, without the elevation and drawing asunder of
which he cannot see, while hard eyes, having no
such provision, are instantly sensible of whatever may
be present in the diaphanous medium. In accord-
ance with this, the olfactory organ is, in such crea-
tures, like the eye, uncovered ; but, in such as breathe,
it is furnished with a cover, which during inspiration
is lifted up, as the veins and pores are then dilated.
On which account, creatures which breathe cannot
smell while in the water, as in order to smell they
must inspire, and while in the water they cannot
possibly inspire.
In fine, odour is derived from what is dry, as
savour is from what is moist ; and the olfactory organ,
when in potentiality, is analogous to that from which
odour is derived.
PRELUDE TD CHAPTER X.
THIS theory of taste and savour is adopted substantively
by modern physiology. Cuvier ' says that " Taste is
only a more delicate kind of Touch ;" and Miiller 2
considers fluid essential to its manifestations. There
f
are three conditions essential to Taste, he observes,
the specific nerve, the excitation of that nerve through
savour, and the solution of the savour in the moisture
of the sapid organ ; for sapid matter to be tasted,
must either be moistened, or else be solvable in the
tongue's moisture. All which implies that, if an
object is very arid, or if the organs of Taste are
incapable of supplying moisture, the percipient will
be sensible, not of sapid but, of tangible qualities only,
such as hot and cold, hard and soft.
1 Rbgne Animal, I. 31.
3 Handbuch der Physiologic, Lib. II. 489.
CHAPTER X.
THE sapid object is a kind of tangible object, and
this is the reason why it does not require, in order to
be perceived, any other medium than the body, for
the Touch requires no other. The body in which is
savour, is the gustable body, and the matter of savour
is in fluid, and fluid is something tangible. Thus,
were we in the water, and were any thing sweet cast
into the water, we should be sensible of the sweetness,
not through the water as a medium but, from its
having been mixed with the water as with a potable
fluid. Colour, however, is not thus made visible from
having been mixed with anything, nor is it made
visible by emanations ; and as the medium, in the
case of colours, plays no part and colour is the visible,
so is savour the gustable. No object, however, with-
out humidity can impart the sense of savour; and,
therefore, every sapid object contains humidity, in an
active or a potential state, as does salt ; for salt is
readily moistened and liquefied by contact with the
tongue.
Now, vision is perceptive of the visible and the
invisible (for darkness, although invisible, is still
CH. X.] ARISTOTLE ON THE VITAL PRINCIPLE. 115
judged of "by vision), and a very bright light (which
is also invisible, although in a manner different from
darkness), and so hearing is equally perceptive of
sound and silence, of which that is audible and this
inaudible, as well as a very loud sound, just as vision
is of a very bright light ; for as a very low sound is,
in a certain sense, inaudible, so is a very loud and
crashing sound. On the other hand, the term in-
visible, used absolutely, is analogous to the term im-
possible upon other subjects, and which may be sig-
nificant of something generated without parts or with
parts ill formed for their office, as an animal without
feet, or a fruit without a kernel. So, too, the taste in
its turn is perceptive both of what is sapid and in-