Aristotle
384-322 B.C.E. - Wrote in Greek
On Sense and the Sensible
Written 350 B.C.E
Translated by J. I. Beare
On Sense and the Sensible
By Aristotle
Section 1
Part 1
Having now definitely considered the soul, by itself, and its several faculties,
we must next make a survey of animals and all living things, in order to
ascertain what functions are peculiar, and what functions are common, to
them. What has been already determined respecting the soul [sc. by itself]
must be assumed throughout. The remaining parts [sc. the attributes of
soul and body conjointly] of our subject must be now dealt with, and we
may begin with those that come first.
The most important attributes of animals, whether common to all
or peculiar to some, are, manifestly, attributes of soul and body in conjunction,
e.g. sensation, memory, passion, appetite and desire in general, and, in
addition pleasure and pain. For these may, in fact, be said to belong to
all animals. But there are, besides these, certain other attributes, of
which some are common to all living things, while others are peculiar to
certain species of animals. The most important of these may be summed up
in four pairs, viz. waking and sleeping, youth and old age, inhalation
and exhalation, life and death. We must endeavour to arrive at a scientific
conception of these, determining their respective natures, and the causes
of their occurrence.
But it behoves the Physical Philosopher to obtain also a clear
view of the first principles of health and disease, inasmuch as neither
health nor disease can exist in lifeless things. Indeed we may say of most
physical inquirers, and of those physicians who study their art philosophically,
that while the former complete their works with a disquisition on medicine,
the latter usually base their medical theories on principles derived from
Physics.
That all the attributes above enumerated belong to soul and body
in conjunction, is obvious; for they all either imply sensation as a concomitant,
or have it as their medium. Some are either affections or states of sensation,
others, means of defending and safe-guarding it, while others, again, involve
its destruction or negation. Now it is clear, alike by reasoning and observation,
that sensation is generated in the soul through the medium of the
body.
We have already, in our treatise On the Soul, explained the nature
of sensation and the act of perceiving by sense, and the reason why this
affection belongs to animals. Sensation must, indeed, be attributed to
all animals as such, for by its presence or absence we distinguish essentially
between what is and what is not an animal.
But coming now to the special senses severally, we may say that
touch and taste necessarily appertain to all animals, touch, for the reason
given in On the Soul, and taste, because of nutrition. It is by taste that
one distinguishes in food the pleasant from the unpleasant, so as to flee
from the latter and pursue the former: and savour in general is an affection
of nutrient matter.
The senses which operate through external media, viz. smelling,
hearing, seeing, are found in all animals which possess the faculty of
locomotion. To all that possess them they are a means of preservation;
their final cause being that such creatures may, guided by antecedent perception,
both pursue their food, and shun things that are bad or destructive. But
in animals which have also intelligence they serve for the attainment of
a higher perfection. They bring in tidings of many distinctive qualities
of things, from which the knowledge of truth, speculative and practical,
is generated in the soul.
Of the two last mentioned, seeing, regarded as a supply for the
primary wants of life, and in its direct effects, is the superior sense;
but for developing intelligence, and in its indirect consequences, hearing
takes the precedence. The faculty of seeing, thanks to the fact that all
bodies are coloured, brings tidings of multitudes of distinctive qualities
of all sorts; whence it is through this sense especially that we perceive
the common sensibles, viz. figure, magnitude, motion, number: while hearing
announces only the distinctive qualities of sound, and, to some few animals,
those also of voice. indirectly, however, it is hearing that contributes
most to the growth of intelligence. For rational discourse is a cause of
instruction in virtue of its being audible, which it is, not directly,
but indirectly; since it is composed of words, and each word is a thought-symbol.
Accordingly, of persons destitute from birth of either sense, the blind
are more intelligent than the deaf and dumb.
Part 2
Of the distinctive potency of each of the faculties of sense enough
has been said already.
But as to the nature of the sensory organs, or parts of the body
in which each of the senses is naturally implanted, inquirers now usually
take as their guide the fundamental elements of bodies. Not, however, finding
it easy to coordinate five senses with four elements, they are at a loss
respecting the fifth sense. But they hold the organ of sight to consist
of fire, being prompted to this view by a certain sensory affection of
whose true cause they are ignorant. This is that, when the eye is pressed
or moved, fire appears to flash from it. This naturally takes place in
darkness, or when the eyelids are closed, for then, too, darkness is
produced.
This theory, however, solves one question only to raise another;
for, unless on the hypothesis that a person who is in his full senses can
see an object of vision without being aware of it, the eye must on this
theory see itself. But then why does the above affection not occur also
when the eye is at rest? The true explanation of this affection, which
will contain the answer to our question, and account for the current notion
that the eye consists of fire, must be determined in the following way:
Things which are smooth have the natural property of shining in darkness,
without, however, producing light. Now, the part of the eye called 'the
black', i.e. its central part, is manifestly smooth. The phenomenon of
the flash occurs only when the eye is moved, because only then could it
possibly occur that the same one object should become as it were two. The
rapidity of the movement has the effect of making that which sees and that
which is seen seem different from one another. Hence the phenomenon does
not occur unless the motion is rapid and takes place in darkness. For it
is in the dark that that which is smooth, e.g. the heads of certain fishes,
and the sepia of the cuttle-fish, naturally shines, and, when the movement
of the eye is slow, it is impossible that that which sees and that which
is seen should appear to be simultaneously two and one. But, in fact, the
eye sees itself in the above phenomenon merely as it does so in ordinary
optical reflexion.
If the visual organ proper really were fire, which is the doctrine
of Empedocles, a doctrine taught also in the Timaeus, and if vision were
the result of light issuing from the eye as from a lantern, why should
the eye not have had the power of seeing even in the dark? It is totally
idle to say, as the Timaeus does, that the visual ray coming forth in the
darkness is quenched. What is the meaning of this 'quenching' of light?
That which, like a fire of coals or an ordinary flame, is hot and dry is,
indeed, quenched by the moist or cold; but heat and dryness are evidently
not attributes of light. Or if they are attributes of it, but belong to
it in a degree so slight as to be imperceptible to us, we should have expected
that in the daytime the light of the sun should be quenched when rain falls,
and that darkness should prevail in frosty weather. Flame, for example,
and ignited bodies are subject to such extinction, but experience shows
that nothing of this sort happens to the sunlight.
Empedocles at times seems to hold that vision is to be explained
as above stated by light issuing forth from the eye, e.g. in the following
passage:-
As when one who purposes going abroad prepares a
lantern,
A gleam of fire blazing through the stormy night,
Adjusting thereto, to screen it from all sorts of
winds,
transparent sides,
Which scatter the breath of the winds as they blow,
While, out through them leaping, the fire,
i.e. all the more subtile part of this,
Shines along his threshold old incessant beams:
So [Divine love] embedded the round "lens", [viz.]
the primaeval fire fenced within the membranes,
In [its own] delicate tissues;
And these fended off the deep surrounding flood,
While leaping forth the fire, i.e. all its more subtile
part-.
Sometimes he accounts for vision thus, but at other times he explains
it by emanations from the visible objects.
Democritus, on the other hand, is right in his opinion that the
eye is of water; not, however, when he goes on to explain seeing as mere
mirroring. The mirroring that takes place in an eye is due to the fact
that the eye is smooth, and it really has its seat not in the eye which
is seen, but in that which sees. For the case is merely one of reflexion.
But it would seem that even in his time there was no scientific knowledge
of the general subject of the formation of images and the phenomena of
reflexion. It is strange too, that it never occurred to him to ask why,
if his theory be true, the eye alone sees, while none of the other things
in which images are reflected do so.
True, then, the visual organ proper is composed of water, yet vision
appertains to it not because it is so composed, but because it is translucent-
a property common alike to water and to air. But water is more easily confined
and more easily condensed than air; wherefore it is that the pupil, i.e.
the eye proper, consists of water. That it does so is proved by facts of
actual experience. The substance which flows from eyes when decomposing
is seen to be water, and this in undeveloped embryos is remarkably cold
and glistening. In sanguineous animals the white of the eye is fat and
oily, in order that the moisture of the eye may be proof against freezing.
Wherefore the eye is of all parts of the body the least sensitive to cold:
no one ever feels cold in the part sheltered by the eyelids. The eyes of
bloodless animals are covered with a hard scale which gives them similar
protection.
It is, to state the matter generally, an irrational notion that
the eye should see in virtue of something issuing from it; that the visual
ray should extend itself all the way to the stars, or else go out merely
to a certain point, and there coalesce, as some say, with rays which proceed
from the object. It would be better to suppose this coalescence to take
place in the fundament of the eye itself. But even this would be mere trifling.
For what is meant by the 'coalescence' of light with light? Or how is it
possible? Coalescence does not occur between any two things taken at random.
And how could the light within the eye coalesce with that outside it? For
the environing membrane comes between them.
That without light vision is impossible has been stated elsewhere;
but, whether the medium between the eye and its objects is air or light,
vision is caused by a process through this medium.
Accordingly, that the inner part of the eye consists of water is
easily intelligible, water being translucent.
Now, as vision outwardly is impossible without [extra-organic]
light, so also it is impossible inwardly [without light within the organ].
There must, therefore, be some translucent medium within the eye, and,
as this is not air, it must be water. The soul or its perceptive part is
not situated at the external surface of the eye, but obviously somewhere
within: whence the necessity of the interior of the eye being translucent,
i.e. capable of admitting light. And that it is so is plain from actual
occurrences. It is matter of experience that soldiers wounded in battle
by a sword slash on the temple, so inflicted as to sever the passages of
[i.e. inward from] the eye, feel a sudden onset of darkness, as if a lamp
had gone out; because what is called the pupil, i.e. the translucent, which
is a sort of inner lamp, is then cut off [from its connexion with the
soul].
Hence, if the facts be at all as here stated, it is clear that-
if one should explain the nature of the sensory organs in this way, i.e.
by correlating each of them with one of the four elements,- we must conceive
that the part of the eye immediately concerned in vision consists of water,
that the part immediately concerned in the perception of sound consists
of air, and that the sense of smell consists of fire. (I say the sense
of smell, not the organ.) For the organ of smell is only potentially that
which the sense of smell, as realized, is actually; since the object of
sense is what causes the actualization of each sense, so that it (the sense)
must (at the instant of actualization) be (actually) that which before
(the moment of actualization) it was potentially. Now, odour is a smoke-like
evaporation, and smoke-like evaporation arises from fire. This also helps
us to understand why the olfactory organ has its proper seat in the environment
of the brain, for cold matter is potentially hot. In the same way must
the genesis of the eye be explained. Its structure is an offshoot from
the brain, because the latter is the moistest and coldest of all the bodily
parts.
The organ of touch proper consists of earth, and the faculty of
taste is a particular form of touch. This explains why the sensory organ
of both touch and taste is closely related to the heart. For the heart
as being the hottest of all the bodily parts, is the counterpoise of the
brain.
This then is the way in which the characteristics of the bodily
organs of sense must be determined.
Part 3
Of the sensibles corresponding to each sensory organ, viz. colour,
sound, odour, savour, touch, we have treated in On the Soul in general
terms, having there determined what their function is, and what is implied
in their becoming actualized in relation to their respective organs. We
must next consider what account we are to give of any one of them; what,
for example, we should say colour is, or sound, or odour, or savour; and
so also respecting [the object of] touch. We begin with
colour.
Now, each of them may be spoken of from two points of view, i.e.
either as actual or as potential. We have in On the Soul explained in what
sense the colour, or sound, regarded as actualized [for sensation] is the
same as, and in what sense it is different from, the correlative sensation,
the actual seeing or hearing. The point of our present discussion is, therefore,
to determine what each sensible object must be in itself, in order to be
perceived as it is in actual consciousness.
We have already in On the Soul stated of Light that it is the colour
of the Translucent, [being so related to it] incidentally; for whenever
a fiery element is in a translucent medium presence there is Light; while
the privation of it is Darkness. But the 'Translucent', as we call it,
is not something peculiar to air, or water, or any other of the bodies
usually called translucent, but is a common 'nature' and power, capable
of no separate existence of its own, but residing in these, and subsisting
likewise in all other bodies in a greater or less degree. As the bodies
in which it subsists must have some extreme bounding surface, so too must
this. Here, then, we may say that Light is a 'nature' inhering in the Translucent
when the latter is without determinate boundary. But it is manifest that,
when the Translucent is in determinate bodies, its bounding extreme must
be something real; and that colour is just this 'something' we are plainly
taught by facts-colour being actually either at the external limit, or
being itself that limit, in bodies. Hence it was that the Pythagoreans
named the superficies of a body its 'hue', for 'hue', indeed, lies at the
limit of the body; but the limit of the body; is not a real thing; rather
we must suppose that the same natural substance which, externally, is the
vehicle of colour exists [as such a possible vehicle] also in the interior
of the body.
Air and water, too [i.e. as well as determinately bounded bodies]
are seen to possess colour; for their brightness is of the nature of colour.
But the colour which air or sea presents, since the body in which it resides
is not determinately bounded, is not the same when one approaches and views
it close by as it is when one regards it from a distance; whereas in determinate
bodies the colour presented is definitely fixed, unless, indeed, when the
atmospheric environment causes it to change. Hence it is clear that that
in them which is susceptible of colour is in both cases the same. It is
therefore the Translucent, according to the degree to which it subsists
in bodies (and it does so in all more or less), that causes them to partake
of colour. But since the colour is at the extremity of the body, it must
be at the extremity of the Translucent in the body. Whence it follows that
we may define colour as the limit of the Translucent in determinately bounded
body. For whether we consider the special class of bodies called translucent,
as water and such others, or determinate bodies, which appear to possess
a fixed colour of their own, it is at the exterior bounding surface that
all alike exhibit their colour.
Now, that which when present in air produces light may be present
also in the Translucent which pervades determinate bodies; or again, it
may not be present, but there may be a privation of it. Accordingly, as
in the case of air the one condition is light, the other darkness, in the
same way the colours White and Black are generated in determinate
bodies.
We must now treat of the other colours, reviewing the several hypotheses
invented to explain their genesis.
(1) It is conceivable that the White and the Black should be juxtaposed
in quantities so minute that [a particle of] either separately would be
invisible, though the joint product [of two particles, a black and a white]
would be visible; and that they should thus have the other colours for
resultants. Their product could, at all events, appear neither white nor
black; and, as it must have some colour, and can have neither of these,
this colour must be of a mixed character- in fact, a species of colour
different from either. Such, then, is a possible way of conceiving the
existence of a plurality of colours besides the White and Black; and we
may suppose that [of this 'plurality'] many are the result of a [numerical]
ratio; for the blacks and whites may be juxtaposed in the ratio of 3 to
2 or of 3 to 4, or in ratios expressible by other numbers; while some may
be juxtaposed according to no numerically expressible ratio, but according
to some relation of excess or defect in which the blacks and whites involved
would be incommensurable quantities; and, accordingly, we may regard all
these colours [viz. all those based on numerical ratios] as analogous to
the sounds that enter into music, and suppose that those involving simple
numerical ratios, like the concords in music, may be those generally regarded
as most agreeable; as, for example, purple, crimson, and some few such
colours, their fewness being due to the same causes which render the concords
few. The other compound colours may be those which are not based on numbers.
Or it may be that, while all colours whatever [except black and white]
are based on numbers, some are regular in this respect, others irregular;
and that the latter [though now supposed to be all based on numbers], whenever
they are not pure, owe this character to a corresponding impurity in [the
arrangement of] their numerical ratios. This then is one conceivable hypothesis
to explain the genesis of intermediate colours.
(2) Another is that the Black and White appear the one through
the medium of the other, giving an effect like that sometimes produced
by painters overlaying a less vivid upon a more vivid colour, as when they
desire to represent an object appearing under water or enveloped in a haze,
and like that produced by the sun, which in itself appears white, but takes
a crimson hue when beheld through a fog or a cloud of smoke. On this hypothesis,
too, a variety of colours may be conceived to arise in the same way as
that already described; for between those at the surface and those underneath
a definite ratio might sometimes exist; in other cases they might stand
in no determinate ratio. To [introduce a theory of colour which would set
all these hypotheses aside, and] say with the ancients that colours are
emanations, and that the visibility of objects is due to such a cause,
is absurd. For they must, in any case, explain sense-perception through
Touch; so that it were better to say at once that visual perception is
due to a process set up by the perceived object in the medium between this
object and the sensory organ; due, that is, to contact [with the medium
affected,] not to emanations.
If we accept the hypothesis of juxtaposition, we must assume not
only invisible magnitude, but also imperceptible time, in order that the
succession in the arrival of the stimulatory movements may be unperceived,
and that the compound colour seen may appear to be one, owing to its successive
parts seeming to present themselves at once. On the hypothesis of superposition,
however, no such assumption is needful: the stimulatory process produced
in the medium by the upper colour, when this is itself unaffected, will
be different in kind from that produced by it when affected by the underlying
colour. Hence it presents itself as a different colour, i.e. as one which
is neither white nor black. So that, if it is impossible to suppose any
magnitude to be invisible, and we must assume that there is some distance
from which every magnitude is visible, this superposition theory, too [i.e.
as well as No. 3 infra], might pass as a real theory of colour-mixture.
Indeed, in the previous case also there is no reason why, to persons at
a distance from the juxtaposed blacks and whites, some one colour should
not appear to present itself as a blend of both. [But it would not be so
on a nearer view], for it will be shown, in a discussion to be undertaken
later on, that there is no magnitude absolutely invisible.
(3) There is a mixture of bodies, however, not merely such as some
suppose, i.e. by juxtaposition of their minimal parts, which, owing to
[the weakness of our] sense, are imperceptible by us, but a mixture by
which they [i.e. the 'matter' of which they consist] are wholly blent together
by interpenetration, as we have described it in the treatise on Mixture,
where we dealt with this subject generally in its most comprehensive aspect.
For, on the supposition we are criticizing, the only totals capable of
being mixed are those which are divisible into minimal parts, [e.g. genera
into individuals] as men, horses, or the [various kinds of] seeds. For
of mankind as a whole the individual man is such a least part; of horses
[as an aggregate] the individual horse. Hence by the juxtaposition of these
we obtain a mixed total, consisting [like a troop of cavalry] of both together;
but we do not say that by such a process any individual man has been mixed
with any individual horse. Not in this way, but by complete interpenetration
[of their matter], must we conceive those things to be mixed which are
not divisible into minima; and it is in the case of these that natural
mixture exhibits itself in its most perfect form. We have explained already
in our discourse 'On Mixture' how such mixture is possible. This being
the true nature of mixture, it is plain that when bodies are mixed their
colours also are necessarily mixed at the same time; and [it is no less
plain] that this is the real cause determining the existence of a plurality
of colours- not superposition or juxtaposition. For when bodies are thus
mixed, their resultant colour presents itself as one and the same at all
distances alike; not varying as it is seen nearer or farther
away.
Colours will thus, too [as well as on the former hypotheses], be
many in number on account of the fact that the ingredients may be combined
with one another in a multitude of ratios; some will be based on determinate
numerical ratios, while others again will have as their basis a relation
of quantitative excess or defect not expressible in integers. And all else
that was said in reference to the colours, considered as juxtaposed or
superposed, may be said of them likewise when regarded as mixed in the
way just described.
Why colours, as well as savours and sounds, consist of species
determinate [in themselves] and not infinite [in number] is a question
which we shall discuss hereafter.
Part 4
We have now explained what colour is, and the reason why there
are many colours; while before, in our work On the Soul, we explained the
nature of sound and voice. We have next to speak of Odour and Savour, both
of which are almost the same physical affection, although they each have
their being in different things. Savours, as a class, display their nature
more clearly to us than Odours, the cause of which is that the olfactory
sense of man is inferior in acuteness to that of the lower animals, and
is, when compared with our other senses, the least perfect of Man's sense
of Touch, on the contrary, excels that of all other animals in fineness,
and Taste is a modification of Touch.
Now the natural substance water per se tends to be tasteless. But
[since without water tasting is impossible] either (a) we must suppose
that water contains in itself [uniformly diffused through it] the various
kinds of savour, already formed, though in amounts so small as to be imperceptible,
which is the doctrine of Empedocles; or (b) the water must be a sort of
matter, qualified, as it were, to produce germs of savours of all kinds,
so that all kinds of savour are generated from the water, though different
kinds from its different parts, or else (c) the water is in itself quite
undifferentiated in respect of savour [whether developed or undeveloped],
but some agent, such for example as one might conceive Heat or the Sun
to be, is the efficient cause of savour.
(a) Of these three hypotheses, the falsity of that held by Empedocles
is only too evident. For we see that when pericarpal fruits are plucked
[from the tree] and exposed in the sun, or subjected to the action of fire,
their sapid juices are changed by the heat, which shows that their qualities
are not due to their drawing anything from the water in the ground, but
to a change which they undergo within the pericarp itself; and we see,
moreover, that these juices, when extracted and allowed to lie, instead
of sweet become by lapse of time harsh or bitter, or acquire savours of
any and every sort; and that, again, by the process of boiling or fermentation
they are made to assume almost all kinds of new savours.
(b) It is likewise impossible that water should be a material qualified
to generate all kinds of Savour germs [so that different savours should
arise out of different parts of the water]; for we see different kinds
of taste generated from the same water, having it as their
nutriment.
(C) It remains, therefore, to suppose that the water is changed
by passively receiving some affection from an external agent. Now, it is
manifest that water does not contract the quality of sapidity from the
agency of Heat alone. For water is of all liquids the thinnest, thinner
even than oil itself, though oil, owing to its viscosity, is more ductile
than water, the latter being uncohesive in its particles; whence water
is more difficult than oil to hold in the hand without spilling. But since
perfectly pure water does not, when subjected to the action of Heat, show
any tendency to acquire consistency, we must infer that some other agency
than heat is the cause of sapidity. For all savours [i.e. sapid liquors]
exhibit a comparative consistency. Heat is, however, a coagent in the
matter.
Now the sapid juices found in pericarpal fruits evidently exist
also in the earth. Hence many of the old natural philosophers assert that
water has qualities like those of the earth through which it flows, a fact
especially manifest in the case of saline springs, for salt is a form of
earth. Hence also when liquids are filtered through ashes, a bitter substance,
the taste they yield is bitter. There are many wells, too, of which some
are bitter, others acid, while others exhibit other tastes of all
kinds.
As was to be anticipated, therefore, it is in the vegetable kingdom
that tastes occur in richest variety. For, like all things else, the Moist,
by nature's law, is affected only by its contrary; and this contrary is
the Dry. Thus we see why the Moist is affected by Fire, which as a natural
substance, is dry. Heat is, however, the essential property of Fire, as
Dryness is of Earth, according to what has been said in our treatise on
the elements. Fire and Earth, therefore, taken absolutely as such, have
no natural power to affect, or be affected by, one another; nor have any
other pair of substances. Any two things can affect, or be affected by,
one another only so far as contrariety to the other resides in either of
them.
As, therefore, persons washing Colours or Savours in a liquid cause
the water in which they wash to acquire such a quality [as that of the
colour or savour], so nature, too, by washing the Dry and Earthy in the
Moist, and by filtering the latter, that is, moving it on by the agency
of heat through the dry and earthy, imparts to it a certain quality. This
affection, wrought by the aforesaid Dry in the Moist, capable of transforming
the sense of Taste from potentiality to actuality, is Savour. Savour brings
into actual exercise the perceptive faculty which pre-existed only in potency.
The activity of sense-perception in general is analogous, not to the process
of acquiring knowledge, but to that of exercising knowledge already
acquired.
That Savours, either as a quality or as the privation of a quality,
belong not to every form of the Dry but to the Nutrient, we shall see by
considering that neither the Dry without the Moist, nor the Moist without
the Dry, is nutrient. For no single element, but only composite substance,
constitutes nutriment for animals. Now, among the perceptible elements
of the food which animals assimilate, the tangible are the efficient causes
of growth and decay; it is qua hot or cold that the food assimilated causes
these; for the heat or cold is the direct cause of growth or decay. It
is qua gustable, however, that the assimilated food supplies nutrition.
For all organisms are nourished by the Sweet [i.e. the 'gustable' proper],
either by itself or in combination with other savours. Of this we must
speak with more precise detail in our work on Generation: for the present
we need touch upon it only so far as our subject here requires. Heat causes
growth, and fits the food-stuff for alimentation; it attracts [into the
organic system] that which is light [viz. the sweet], while the salt and
bitter it rejects because of their heaviness. In fact, whatever effects
external heat produces in external bodies, the same are produced by their
internal heat in animal and vegetable organisms. Hence it is [i.e. by the
agency of heat as described] that nourishment is effected by the sweet.
The other savours are introduced into and blended in food [naturally] on
a principle analogous to that on which the saline or the acid is used artificially,
i.e. for seasoning. These latter are used because they counteract the tendency
of the sweet to be too nutrient, and to float on the
stomach.
As the intermediate colours arise from the mixture of white and
black, so the intermediate savours arise from the Sweet and Bitter; and
these savours, too, severally involve either a definite ratio, or else
an indefinite relation of degree, between their components, either having
certain integral numbers at the basis of their mixture, and, consequently,
of their stimulative effect, or else being mixed in proportions not arithmetically
expressible. The tastes which give pleasure in their combination are those
which have their components joined in a definite ratio.
The sweet taste alone is Rich, [therefore the latter may be regarded
as a variety of the former], while [so far as both imply privation of the
Sweet] the Saline is fairly identical with the Bitter. Between the extremes
of sweet and bitter come the Harsh, the Pungent, the Astringent, and the
Acid. Savours and Colours, it will be observed, contain respectively about
the same number of species. For there are seven species of each, if, as
is reasonable, we regard Dun [or Grey] as a variety of Black (for the alternative
is that Yellow should be classed with White, as Rich with Sweet); while
[the irreducible colours, viz.] Crimson, Violet, leek-Green, and deep Blue,
come between White and Black, and from these all others are derived by
mixture.
Again, as Black is a privation of White in the Translucent, so
Saline or Bitter is a privation of Sweet in the Nutrient Moist. This explains
why the ash of all burnt things is bitter; for the potable [sc. the sweet]
moisture has been exuded from them.
Democritus and most of the natural philosophers who treat of sense-perception
proceed quite irrationally, for they represent all objects of sense as
objects of Touch. Yet, if this is really so, it clearly follows that each
of the other senses is a mode of Touch; but one can see at a glance that
this is impossible.
Again, they treat the percepts common to all senses as proper to
one. For [the qualities by which they explain taste viz.] Magnitude and
Figure, Roughness and Smoothness, and, moreover, the Sharpness and Bluntness
found in solid bodies, are percepts common to all the senses, or if not
to all, at least to Sight and Touch. This explains why it is that the senses
are liable to err regarding them, while no such error arises respecting
their proper sensibles; e.g. the sense of Seeing is not deceived as to
Colour, nor is that of Hearing as to Sound.
On the other hand, they reduce the proper to common sensibles,
as Democritus does with White and Black; for he asserts that the latter
is [a mode of the] rough, and the former [a mode of the] smooth, while
he reduces Savours to the atomic figures. Yet surely no one sense, or,
if any, the sense of Sight rather than any other, can discern the common
sensibles. But if we suppose that the sense of Taste is better able to
do so, then- since to discern the smallest objects in each kind is what
marks the acutest sense-Taste should have been the sense which best perceived
the common sensibles generally, and showed the most perfect power of discerning
figures in general.
Again, all the sensibles involve contrariety; e.g. in Colour White
is contrary to Black, and in Savours Bitter is contrary to Sweet; but no
one figure is reckoned as contrary to any other figure. Else, to which
of the possible polygonal figures [to which Democritus reduces Bitter]
is the spherical figure [to which he reduces Sweet]
contrary?
Again, since figures are infinite in number, savours also should
be infinite; [the possible rejoinder- 'that they are so, only that some
are not perceived'- cannot be sustained] for why should one savour be perceived,
and another not?
This completes our discussion of the object of Taste, i.e. Savour;
for the other affections of Savours are examined in their proper place
in connection with the natural history of Plants.
On Sense and the Sensible
By Aristotle
Section 2
Part 5
Our conception of the nature of Odours must be analogous to that of Savours;
inasmuch as the Sapid Dry effects in air and water alike, but in a different
province of sense, precisely what the Dry effects in the Moist of water
only. We customarily predicate Translucency of both air and water in common;
but it is not qua translucent that either is a vehicle of odour, but qua
possessed of a power of washing or rinsing [and so imbibing] the Sapid
Dryness.
For the object of Smell exists not in air only: it also exists
in water. This is proved by the case of fishes and testacea, which are
seen to possess the faculty of smell, although water contains no air (for
whenever air is generated within water it rises to the surface), and these
creatures do not respire. Hence, if one were to assume that air and water
are both moist, it would follow that Odour is the natural substance consisting
of the Sapid Dry diffused in the Moist, and whatever is of this kind would
be an object of Smell.
That the property of odorousness is based upon the Sapid may be
seen by comparing the things which possess with those which do not possess
odour. The elements, viz. Fire, Air, Earth, Water, are inodorous, because
both the dry and the moist among them are without sapidity, unless some
added ingredient produces it. This explains why sea-water possesses odour,
for [unlike 'elemental' water] it contains savour and dryness. Salt, too,
is more odorous than natron, as the oil which exudes from the former proves,
for natron is allied to ['elemental'] earth more nearly than salt. Again,
a stone is inodorous, just because it is tasteless, while, on the contrary,
wood is odorous, because it is sapid. The kinds of wood, too, which contain
more ['elemental'] water are less odorous than others. Moreover, to take
the case of metals, gold is inodorous because it is without taste, but
bronze and iron are odorous; and when the [sapid] moisture has been burnt
out of them, their slag is, in all cases, less odorous the metals [than
the metals themselves]. Silver and tin are more odorous than the one class
of metals, less so than the other, inasmuch as they are water [to a greater
degree than the former, to a less degree than the latter].
Some writers look upon Fumid exhalation, which is a compound of
Earth and Air, as the essence of Odour. [Indeed all are inclined to rush
to this theory of Odour.] Heraclitus implied his adherence to it when he
declared that if all existing things were turned into Smoke, the nose would
be the organ to discern them with. All writers incline to refer odour to
this cause [sc. exhalation of some sort], but some regard it as aqueous,
others as fumid, exhalation; while others, again, hold it to be either.
Aqueous exhalation is merely a form of moisture, but fumid exhalation is,
as already remarked, composed of Air and Earth. The former when condensed
turns into water; the latter, in a particular species of earth. Now, it
is unlikely that odour is either of these. For vaporous exhalation consists
of mere water [which, being tasteless, is inodorous]; and fumid exhalation
cannot occur in water at all, though, as has been before stated, aquatic
creatures also have the sense of smell.
Again, the exhalation theory of odour is analogous to the theory
of emanations. If, therefore, the latter is untenable, so, too, is the
former.
It is clearly conceivable that the Moist, whether in air (for air,
too, is essentially moist) or in water, should imbibe the influence of,
and have effects wrought in it by, the Sapid Dryness. Moreover, if the
Dry produces in moist media, i.e. water and air, an effect as of something
washed out in them, it is manifest that odours must be something analogous
to savours. Nay, indeed, this analogy is, in some instances, a fact [registered
in language]; for odours as well as savours are spoken of as pungent, sweet,
harsh, astringent rich [='savoury']; and one might regard fetid smells
as analogous to bitter tastes; which explains why the former are offensive
to inhalation as the latter are to deglutition. It is clear, therefore,
that Odour is in both water and air what Savour is in water alone. This
explains why coldness and freezing render Savours dull, and abolish odours
altogether; for cooling and freezing tend to annul the kinetic heat which
helps to fabricate sapidity.
There are two species of the Odorous. For the statement of certain
writers that the odorous is not divisible into species is false; it is
so divisible. We must here define the sense in which these species are
to be admitted or denied.
One class of odours, then, is that which runs parallel, as has
been observed, to savours: to odours of this class their pleasantness or
unpleasantness belongs incidentally. For owing to the fact that Savours
are qualities of nutrient matter, the odours connected with these [e.g.
those of a certain food] are agreeable as long as animals have an appetite
for the food, but they are not agreeable to them when sated and no longer
in want of it; nor are they agreeable, either, to those animals that do
not like the food itself which yields the odours. Hence, as we observed,
these odours are pleasant or unpleasant incidentally, and the same reasoning
explains why it is that they are perceptible to all animals in
common.
The other class of odours consists of those agreeable in their
essential nature, e.g. those of flowers. For these do not in any degree
stimulate animals to food, nor do they contribute in any way to appetite;
their effect upon it, if any, is rather the opposite. For the verse of
Strattis ridiculing Euripides-
Use not perfumery to flavour soup, contains a
truth.
Those who nowadays introduce such flavours into beverages deforce
our sense of pleasure by habituating us to them, until, from two distinct
kinds of sensations combined, pleasure arises as it might from one simple
kind.
Of this species of odour man alone is sensible; the other, viz.
that correlated with Tastes, is, as has been said before, perceptible also
to the lower animals. And odours of the latter sort, since their pleasureableness
depends upon taste, are divided into as many species as there are different
tastes; but we cannot go on to say this of the former kind of odour, since
its nature is agreeable or disagreeable per se. The reason why the perception
of such odours is peculiar to man is found in the characteristic state
of man's brain. For his brain is naturally cold, and the blood which it
contains in its vessels is thin and pure but easily cooled (whence it happens
that the exhalation arising from food, being cooled by the coldness of
this region, produces unhealthy rheums); therefore it is that odours of
such a species have been generated for human beings, as a safeguard to
health. This is their sole function, and that they perform it is evident.
For food, whether dry or moist, though sweet to taste, is often unwholesome;
whereas the odour arising from what is fragrant, that odour which is pleasant
in its own right, is, so to say, always beneficial to persons in any state
of bodily health whatever.
For this reason, too, the perception of odour [in general] effected
through respiration, not in all animals, but in man and certain other sanguineous
animals, e.g. quadrupeds, and all that participate freely in the natural
substance air; because when odours, on account of the lightness of the
heat in them, mount to the brain, the health of this region is thereby
promoted. For odour, as a power, is naturally heat-giving. Thus Nature
has employed respiration for two purposes: primarily for the relief thereby
brought to the thorax, secondarily for the inhalation of odour. For while
an animal is inhaling,- odour moves in through its nostrils, as it were
'from a side-entrance.'
But the perception of the second class of odours above described
[does not belong to all animal, but] is confined to human beings, because
man's brain is, in proportion to his whole bulk, larger and moister than
the brain of any other animal. This is the reason of the further fact that
man alone, so to speak, among animals perceives and takes pleasure in the
odours of flowers and such things. For the heat and stimulation set up
by these odours are commensurate with the excess of moisture and coldness
in his cerebral region. On all the other animals which have lungs, Nature
has bestowed their due perception of one of the two kinds of odour [i.e.
that connected with nutrition] through the act of respiration, guarding
against the needless creation of two organs of sense; for in the fact that
they respire the other animals have already sufficient provision for their
perception of the one species of odour only, as human beings have for their
perception of both.
But that creatures which do not respire have the olfactory sense
is evident. For fishes, and all insects as a class, have, thanks to the
species of odour correlated with nutrition, a keen olfactory sense of their
proper food from a distance, even when they are very far away from it;
such is the case with bees, and also with the class of small ants, which
some denominate knipes. Among marine animals, too, the murex and many other
similar animals have an acute perception of their food by its
odour.
It is not equally certain what the organ is whereby they so perceive.
This question, of the organ whereby they perceive odour, may well cause
a difficulty, if we assume that smelling takes place in animals only while
respiring (for that this is the fact is manifest in all the animals which
do respire), whereas none of those just mentioned respires, and yet they
have the sense of smell- unless, indeed, they have some other sense not
included in the ordinary five. This supposition is, however, impossible.
For any sense which perceives odour is a sense of smell, and this they
do perceive, though probably not in the same way as creatures which respire,
but when the latter are respiring the current of breath removes something
that is laid like a lid upon the organ proper (which explains why they
do not perceive odours when not respiring); while in creatures which do
not respire this is always off: just as some animals have eyelids on their
eyes, and when these are not raised they cannot see, whereas hard-eyed
animals have no lids, and consequently do not need, besides eyes, an agency
to raise the lids, but see straightway [without intermission] from the
actual moment at which it is first possible for them to do so [i.e. from
the moment when an object first comes within their field of
vision].
Consistently with what has been said above, not one of the lower
animals shows repugnance to the odour of things which are essentially ill-smelling,
unless one of the latter is positively pernicious. They are destroyed,
however, by these things, just as human beings are; i.e. as human beings
get headaches from, and are often asphyxiated by, the fumes of charcoal,
so the lower animals perish from the strong fumes of brimstone and bituminous
substances; and it is owing to experience of such effects that they shun
these. For the disagreeable odour in itself they care nothing whatever
(though the odours of many plants are essentially disagreeable), unless,
indeed, it has some effect upon the taste of their food.
The senses making up an odd number, and an odd number having always
a middle unit, the sense of smell occupies in itself as it were a middle
position between the tactual senses, i.e. Touch and Taste, and those which
perceive through a medium, i.e. Sight and Hearing. Hence the object of
smell, too, is an affection of nutrient substances (which fall within the
class of Tangibles), and is also an affection of the audible and the visible;
whence it is that creatures have the sense of smell both in air and water.
Accordingly, the object of smell is something common to both of these provinces,
i.e. it appertains both to the tangible on the one hand, and on the other
to the audible and translucent. Hence the propriety of the figure by which
it has been described by us as an immersion or washing of dryness in the
Moist and Fluid. Such then must be our account of the sense in which one
is or is not entitled to speak of the odorous as having
species.
The theory held by certain of the Pythagoreans, that some animals
are nourished by odours alone, is unsound. For, in the first place, we
see that food must be composite, since the bodies nourished by it are not
simple. This explains why waste matter is secreted from food, either within
the organisms, or, as in plants, outside them. But since even water by
itself alone, that is, when unmixed, will not suffice for food- for anything
which is to form a consistency must be corporeal-, it is still much less
conceivable that air should be so corporealized [and thus fitted to be
food]. But, besides this, we see that all animals have a receptacle for
food, from which, when it has entered, the body absorbs it. Now, the organ
which perceives odour is in the head, and odour enters with the inhalation
of the breath; so that it goes to the respiratory region. It is plain,
therefore, that odour, qua odour, does not contribute to nutrition; that,
however, it is serviceable to health is equally plain, as well by immediate
perception as from the arguments above employed; so that odour is in relation
to general health what savour is in the province of nutrition and in relation
to the bodies nourished.
This then must conclude our discussion of the several organs of
sense-perception.
Part 6
One might ask: if every body is infinitely divisible, are its sensible
qualities- Colour, Savour, Odour, Sound, Weight, Cold or Heat, [Heaviness
or] Lightness, Hardness or Softness-also infinitely divisible? Or, is this
impossible?
[One might well ask this question], because each of them is productive
of sense-perception, since, in fact, all derive their name [of 'sensible
qualities'] from the very circumstance of their being able to stimulate
this. Hence, [if this is so] both our perception of them should likewise
be divisible to infinity, and every part of a body [however small] should
be a perceptible magnitude. For it is impossible, e.g. to see a thing which
is white but not of a certain magnitude.
Since if it were not so, [if its sensible qualities were not divisible,
pari passu with body], we might conceive a body existing but having no
colour, or weight, or any such quality; accordingly not perceptible at
all. For these qualities are the objects of sense-perception. On this supposition,
every perceptible object should be regarded as composed not of perceptible
[but of imperceptible] parts. Yet it must [be really composed of perceptible
parts], since assuredly it does not consist of mathematical [and therefore
purely abstract and non-sensible] quantities. Again, by what faculty should
we discern and cognize these [hypothetical real things without sensible
qualities]? Is it by Reason? But they are not objects of Reason; nor does
reason apprehend objects in space, except when it acts in conjunction with
sense-perception. At the same time, if this be the case [that there are
magnitudes, physically real, but without sensible quality], it seems to
tell in favour of the atomistic hypothesis; for thus, indeed, [by accepting
this hypothesis], the question [with which this chapter begins] might be
solved [negatively]. But it is impossible [to accept this hypothesis].
Our views on the subject of atoms are to be found in our treatise on
Movement.
The solution of these questions will bring with it also the answer
to the question why the species of Colour, Taste, Sound, and other sensible
qualities are limited. For in all classes of things lying between extremes
the intermediates must be limited. But contraries are extremes, and every
object of sense-perception involves contrariety: e.g. in Colour, White
x Black; in Savour, Sweet x Bitter, and in all the other sensibles also
the contraries are extremes. Now, that which is continuous is divisible
into an infinite number of unequal parts, but into a finite number of equal
parts, while that which is not per se continuous is divisible into species
which are finite in number. Since then, the several sensible qualities
of things are to be reckoned as species, while continuity always subsists
in these, we must take account of the difference between the Potential
and the Actual. It is owing to this difference that we do not [actually]
see its ten-thousandth part in a grain of millet, although sight has embraced
the whole grain within its scope; and it is owing to this, too, that the
sound contained in a quarter-tone escapes notice, and yet one hears the
whole strain, inasmuch as it is a continuum; but the interval between the
extreme sounds [that bound the quarter-tone] escapes the ear [being only
potentially audible, not actually]. So, in the case of other objects of
sense, extremely small constituents are unnoticed; because they are only
potentially not actually [perceptible e.g.] visible, unless when they have
been parted from the wholes. So the footlength too exists potentially in
the two-foot length, but actually only when it has been separated from
the whole. But objective increments so small as those above might well,
if separated from their totals, [instead of achieving 'actual' exisistence]
be dissolved in their environments, like a drop of sapid moisture poured
out into the sea. But even if this were not so [sc. with the objective
magnitude], still, since the [subjective] of sense-perception is not perceptible
in itself, nor capable of separate existence (since it exists only potentially
in the more distinctly perceivable whole of sense-perception), so neither
will it be possible to perceive [actually] its correlatively small object
[sc. its quantum of pathema or sensible quality] when separated from the
object-total. But yet this [small object] is to be considered as perceptible:
for it is both potentially so already [i.e. even when alone], and destined
to be actually so when it has become part of an aggregate. Thus, therefore,
we have shown that some magnitudes and their sensible qualities escape
notice, and the reason why they do so, as well as the manner in which they
are still perceptible or not perceptible in such cases. Accordingly then
when these [minutely subdivided] sensibles have once again become aggregated
in a whole in such a manner, relatively to one another, as to be perceptible
actually, and not merely because they are in the whole, but even apart
from it, it follows necessarily [from what has been already stated] that
their sensible qualities, whether colours or tastes or sounds, are limited
in number.
One might ask:- do the objects of sense-perception, or the movements
proceeding from them ([since movements there are,] in whichever of the
two ways [viz. by emanations or by stimulatory kinesis] sense-perception
takes place), when these are actualized for perception, always arrive first
at a spatial middle point [between the sense-organ and its object], as
Odour evidently does, and also Sound? For he who is nearer [to the odorous
object] perceives the Odour sooner [than who is farther away], and the
Sound of a stroke reaches us some time after it has been struck. Is it
thus also with an object seen, and with Light? Empedocles, for example,
says that the Light from the Sun arrives first in the intervening space
before it comes to the eye, or reaches the Earth. This might plausibly
seem to be the case. For whatever is moved [in space], is moved from one
place to another; hence there must be a corresponding interval of time
also in which it is moved from the one place to the other. But any given
time is divisible into parts; so that we should assume a time when the
sun's ray was not as yet seen, but was still travelling in the middle
space.
Now, even if it be true that the acts of 'hearing' and 'having
heard', and, generally, those of 'perceiving' and 'having perceived', form
co-instantaneous wholes, in other words, that acts of sense-perception
do not involve a process of becoming, but have their being none the less
without involving such a process; yet, just as, [in the case of sound],
though the stroke which causes the Sound has been already struck, the Sound
is not yet at the ear (and that this last is a fact is further proved by
the transformation which the letters [viz. the consonants as heard] undergo
[in the case of words spoken from a distance], implying that the local
movement [involved in Sound] takes place in the space between [us and the
speaker]; for the reason why [persons addressed from a distance] do not
succeed in catching the sense of what is said is evidently that the air
[sound wave] in moving towards them has its form changed) [granting this,
then, the question arises]: is the same also true in the case of Colour
and Light? For certainly it is not true that the beholder sees, and the
object is seen, in virtue of some merely abstract relationship between
them, such as that between equals. For if it were so, there would be no
need [as there is] that either [the beholder or the thing beheld] should
occupy some particular place; since to the equalization of things their
being near to, or far from, one another makes no difference.
Now this [travelling through successive positions in the medium]
may with good reason take place as regards Sound and Odour, for these,
like [their media] Air and Water, are continuous, but the movement of both
is divided into parts. This too is the ground of the fact that the object
which the person first in order of proximity hears or smells is the same
as that which each subsequent person perceives, while yet it is not the
same.
Some, indeed, raise a question also on these very points; they
declare it impossible that one person should hear, or see, or smell, the
same object as another, urging the impossibility of several persons in
different places hearing or smelling [the same object], for the one same
thing would [thus] be divided from itself. The answer is that, in perceiving
the object which first set up the motion- e.g. a bell, or frankincense,
or fire- all perceive an object numerically one and the same; while, of
course, in the special object perceived they perceive an object numerically
different for each, though specifically the same for all; and this, accordingly,
explains how it is that many persons together see, or smell, or hear [the
same object]. These things [the odour or sound proper] are not bodies,
but an affection or process of some kind (otherwise this [viz. simultaneous
perception of the one object by many] would not have been, as it is, a
fact of experience) though, on the other hand, they each imply a body [as
their cause].
But [though sound and odour may travel,] with regard to Light the
case is different. For Light has its raison d'etre in the being [not becoming]
of something, but it is not a movement. And in general, even in qualitative
change the case is different from what it is in local movement [both being
different species of kinesis]. Local movements, of course, arrive first
at a point midway before reaching their goal (and Sound, it is currently
believed, is a movement of something locally moved), but we cannot go on
to assert this [arrival at a point midway] like manner of things which
undergo qualitative change. For this kind of change may conceivably take
place in a thing all at once, without one half of it being changed before
the other; e.g. it is conceivable that water should be frozen simultaneously
in every part. But still, for all that, if the body which is heated or
frozen is extensive, each part of it successively is affected by the part
contiguous, while the part first changed in quality is so changed by the
cause itself which originates the change, and thus the change throughout
the whole need not take place coinstantaneously and all at once. Tasting
would have been as smelling now is, if we lived in a liquid medium, and
perceived [the sapid object] at a distance, before touching
it.
Naturally, then, the parts of media between a sensory organ and
its object are not all affected at once- except in the case of Light [illumination]
for the reason above stated, and also in the case of seeing, for the same
reason; for Light is an efficient cause of seeing.
Part 7
Another question respecting sense-perception is as follows: assuming,
as is natural, that of two [simultaneous] sensory stimuli the stronger
always tends to extrude the weaker [from consciousness], is it conceivable
or not that one should be able to discern two objects coinstantaneously
in the same individual time? The above assumption explains why persons
do not perceive what is brought before their eyes, if they are at the time
deep in thought, or in a fright, or listening to some loud noise. This
assumption, then, must be made, and also the following: that it is easier
to discern each object of sense when in its simple form than when an ingredient
in a mixture; easier, for example, to discern wine when neat than when
blended, and so also honey, and [in other provinces] a colour, or to discern
the nete by itself alone, than [when sounded with the hypate] in the octave;
the reason being that component elements tend to efface [the distinctive
characteristics of] one another. Such is the effect [on one another] of
all ingredients of which, when compounded, some one thing is
formed.
If, then, the greater stimulus tends to expel the less, it necessarily
follows that, when they concur, this greater should itself too be less
distinctly perceptible than if it were alone, since the less by blending
with it has removed some of its individuality, according to our assumption
that simple objects are in all cases more distinctly
perceptible.
Now, if the two stimuli are equal but heterogeneous, no perception
of either will ensue; they will alike efface one another's characteristics.
But in such a case the perception of either stimulus in its simple form
is impossible. Hence either there will then be no sense-perception at all,
or there will be a perception compounded of both and differing from either.
The latter is what actually seems to result from ingredients blended together,
whatever may be the compound in which they are so mixed.
Since, then, from some concurrent [sensory stimuli] a resultant
object is produced, while from others no such resultant is produced, and
of the latter sort are those things which belong to different sense provinces
(for only those things are capable of mixture whose extremes are contraries,
and no one compound can be formed from, e.g. White and Sharp, except indirectly,
i.e. not as a concord is formed of Sharp and Grave); there follows logically
the impossibility of discerning such concurrent stimuli coinstantaneously.
For we must suppose that the stimuli, when equal, tend alike to efface
one another, since no one [form of stimulus] results from them; while,
if they are unequal, the stronger alone is distinctly
perceptible.
Again, the soul would be more likely to perceive coinstantaneously,
with one and the same sensory act, two things in the same sensory province,
such as the Grave and the Sharp in sound; for the sensory stimulation in
this one province is more likely to be unitemporal than that involving
two different provinces, as Sight and Hearing. But it is impossible to
perceive two objects coinstantaneously in the same sensory act unless they
have been mixed, [when, however, they are no longer two], for their amalgamation
involves their becoming one, and the sensory act related to one object
is itself one, and such act, when one, is, of course, coinstantaneous with
itself. Hence, when things are mixed we of necessity perceive them coinstantaneously:
for we perceive them by a perception actually one. For an object numerically
one means that which is perceived by a perception actually one, whereas
an object specifically one means that which is perceived by a sensory act
potentially one [i.e. by an energeia of the same sensuous faculty]. If
then the actualized perception is one, it will declare its data to be one
object; they must, therefore, have been mixed. Accordingly, when they have
not been mixed, the actualized perceptions which perceive them will be
two; but [if so, their perception must be successive not coinstantaneous,
for] in one and the same faculty the perception actualized at any single
moment is necessarily one, only one stimulation or exertion of a single
faculty being possible at a single instant, and in the case supposed here
the faculty is one. It follows, therefore, that we cannot conceive the
possibility of perceiving two distinct objects coinstantaneously with one
and the same sense.
But if it be thus impossible to perceive coinstantaneously two
objects in the same province of sense if they are really two, manifestly
it is still less conceivable that we should perceive coinstantaneously
objects in two different sensory provinces, as White and Sweet. For it
appears that when the Soul predicates numerical unity it does so in virtue
of nothing else than such coinstantaneous perception [of one object, in
one instant, by one energeia]: while it predicates specific unity in virtue
of [the unity of] the discriminating faculty of sense together with [the
unity of] the mode in which this operates. What I mean, for example, is
this; the same sense no doubt discerns White and Black, [which are hence
generically one] though specifically different from one another, and so,
too, a faculty of sense self-identical, but different from the former,
discerns Sweet and Bitter; but while both these faculties differ from one
another [and each from itself] in their modes of discerning either of their
respective contraries, yet in perceiving the co-ordinates in each province
they proceed in manners analogous to one another; for instance, as Taste
perceives Sweet, so Sight perceives White; and as the latter perceives
Black, so the former perceives Bitter.
Again, if the stimuli of sense derived from Contraries are themselves
Contrary, and if Contraries cannot be conceived as subsisting together
in the same individual subject, and if Contraries, e.g. Sweet and Bitter,
come under one and the same sense-faculty, we must conclude that it is
impossible to discern them coinstantaneously. It is likewise clearly impossible
so to discern such homogeneous sensibles as are not [indeed] Contrary,
[but are yet of different species]. For these are, [in the sphere of colour,
for instance], classed some with White, others with Black, and so it is,
likewise, in the other provinces of sense; for example, of savours, some
are classed with Sweet, and others with Bitter. Nor can one discern the
components in compounds coinstantaneously (for these are ratios of Contraries,
as e.g. the Octave or the Fifth); unless, indeed, on condition of perceiving
them as one. For thus, and not otherwise, the ratios of the extreme sounds
are compounded into one ratio: since we should have together the ratio,
on the one hand, of Many to Few or of Odd to Even, on the other, that of
Few to Many or of Even to Odd [and these, to be perceived together, must
be unified].
If, then, the sensibles denominated co-ordinates though in different
provinces of sense (e.g. I call Sweet and White co-ordinates though in
different provinces) stand yet more aloof, and differ more, from one another
than do any sensibles in the same province; while Sweet differs from White
even more than Black does from White, it is still less conceivable that
one should discern them [viz. sensibles in different sensory provinces
whether co-ordinates or not] coinstantaneously than sensibles which are
in the same province. Therefore, if coinstantaneous perception of the latter
be impossible, that of the former is a fortiori impossible.
Some of the writers who treat of concords assert that the sounds
combined in these do not reach us simultaneously, but only appear to do
so, their real successiveness being unnoticed whenever the time it involves
is [so small as to be] imperceptible. Is this true or not? One might perhaps,
following this up, go so far as to say that even the current opinion that
one sees and hears coinstantaneously is due merely to the fact that the
intervals of time [between the really successive perceptions of sight and
hearing] escape observation. But this can scarcely be true, nor is it conceivable
that any portion of time should be [absolutely] imperceptible, or that
any should be absolutely unnoticeable; the truth being that it is possible
to perceive every instant of time. [This is so]; because, if it is inconceivable
that a person should, while perceiving himself or aught else in a continuous
time, be at any instant unaware of his own existence; while, obviously,
the assumption, that there is in the time-continuum a time so small as
to be absolutely imperceptible, carries the implication that a person would,
during such time, be unaware of his own existence, as well as of his seeing
and perceiving; [this assumption must be false].
Again, if there is any magnitude, whether time or thing, absolutely
imperceptible owing to its smallness, it follows that there would not be
either a thing which one perceives, or a time in which one perceives it,
unless in the sense that in some part of the given time he sees some part
of the given thing. For [let there be a line ab, divided into two parts
at g, and let this line represent a whole object and a corresponding whole
time. Now,] if one sees the whole line, and perceives it during a time
which forms one and the same continuum, only in the sense that he does
so in some portion of this time, let us suppose the part gb, representing
a time in which by supposition he was perceiving nothing, cut off from
the whole. Well, then, he perceives in a certain part [viz. in the remainder]
of the time, or perceives a part [viz. the remainder] of the line, after
the fashion in which one sees the whole earth by seeing some given part
of it, or walks in a year by walking in some given part of the year. But
[by hypothesis] in the part bg he perceives nothing: therefore, in fact,
he is said to perceive the whole object and during the whole time simply
because he perceives [some part of the object] in some part of the time
ab. But the same argument holds also in the case of ag [the remainder,
regarded in its turn as a whole]; for it will be found [on this theory
of vacant times and imperceptible magnitudes] that one always perceives
only in some part of a given whole time, and perceives only some part of
a whole magnitude, and that it is impossible to perceive any [really] whole
[object in a really whole time; a conclusion which is absurd, as it would
logically annihilate the perception of both Objects and
Time].
Therefore we must conclude that all magnitudes are perceptible,
but their actual dimensions do not present themselves immediately in their
presentation as objects. One sees the sun, or a four-cubit rod at a distance,
as a magnitude, but their exact dimensions are not given in their visual
presentation: nay, at times an object of sight appears indivisible, but
[vision like other special senses, is fallible respecting 'common sensibles',
e.g. magnitude, and] nothing that one sees is really indivisible. The reason
of this has been previously explained. It is clear then, from the above
arguments, that no portion of time is imperceptible.
But we must here return to the question proposed above for discussion,
whether it is possible or impossible to perceive several objects coinstantaneously;
by 'coinstantaneously' I mean perceiving the several objects in a time
one and indivisible relatively to one another, i.e. indivisible in a sense
consistent with its being all a continuum.
First, then, is it conceivable that one should perceive the different
things coinstantaneously, but each with a different part of the Soul? Or
[must we object] that, in the first place, to begin with the objects of
one and the same sense, e.g. Sight, if we assume it [the Soul qua exercising
Sight] to perceive one colour with one part, and another colour with a
different part, it will have a plurality of parts the same in species,
[as they must be,] since the objects which it thus perceives fall within
the same genus?
Should any one [to illustrate how the Soul might have in it two
different parts specifically identical, each directed to a set of aistheta
the same in genus with that to which the other is directed] urge that,
as there are two eyes, so there may be in the Soul something analogous,
[the reply is] that of the eyes, doubtless, some one organ is formed, and
hence their actualization in perception is one; but if this is so in the
Soul, then, in so far as what is formed of both [i.e. of any two specifically
identical parts as assumed] is one, the true perceiving subject also will
be one, [and the contradictory of the above hypothesis (of different parts
of Soul remaining engaged in simultaneous perception with one sense) is
what emerges from the analogy]; while if the two parts of Soul remain separate,
the analogy of the eyes will fail, [for of these some one is really
formed].
Furthermore, [on the supposition of the need of different parts
of Soul, co-operating in each sense, to discern different objects coinstantaneously],
the senses will be each at the same time one and many, as if we should
say that they were each a set of diverse sciences; for neither will an
'activity' exist without its proper faculty, nor without activity will
there be sensation.
But if the Soul does not, in the way suggested [i.e. with different
parts of itself acting simultaneously], perceive in one and the same individual
time sensibles of the same sense, a fortiori it is not thus that it perceives
sensibles of different senses. For it is, as already stated, more conceivable
that it should perceive a plurality of the former together in this way
than a plurality of heterogeneous objects.
If then, as is the fact, the Soul with one part perceives Sweet,
with another, White, either that which results from these is some one part,
or else there is no such one resultant. But there must be such an one,
inasmuch as the general faculty of sense-perception is one. What one object,
then, does that one faculty [when perceiving an object, e.g. as both White
and Sweet] perceive? [None]; for assuredly no one object arises by composition
of these [heterogeneous objects, such as White and Sweet]. We must conclude,
therefore, that there is, as has been stated before, some one faculty in
the soul with which the latter perceives all its percepts, though it perceives
each different genus of sensibles through a different
organ.
May we not, then, conceive this faculty which perceives White and
Sweet to be one qua indivisible [sc. qua combining its different simultaneous
objects] in its actualization, but different, when it has become divisible
[sc. qua distinguishing its different simultaneous objects] in its
actualization?
Or is what occurs in the case of the perceiving Soul conceivably
analogous to what holds true in that of the things themselves? For the
same numerically one thing is white and sweet, and has many other qualities,
[while its numerical oneness is not thereby prejudiced] if the fact is
not that the qualities are really separable in the object from one another,
but that the being of each quality is different [from that of every other].
In the same way therefore we must assume also, in the case of the Soul,
that the faculty of perception in general is in itself numerically one
and the same, but different [differentiated] in its being; different, that
is to say, in genus as regards some of its objects, in species as regards
others. Hence too, we may conclude that one can perceive [numerically different
objects] coinstantaneously with a faculty which is numerically one and
the same, but not the same in its relationship [sc. according as the objects
to which it is directed are not the same].
That every sensible object is a magnitude, and that nothing which
it is possible to perceive is indivisible, may be thus shown. The distance
whence an object could not be seen is indeterminate, but that whence it
is visible is determinate. We may say the same of the objects of Smelling
and Hearing, and of all sensibles not discerned by actual contact. Now,
there is, in the interval of distance, some extreme place, the last from
which the object is invisible, and the first from which it is visible.
This place, beyond which if the object be one cannot perceive it, while
if the object be on the hither side one must perceive it, is, I presume,
itself necessarily indivisible. Therefore, if any sensible object be indivisible,
such object, if set in the said extreme place whence imperceptibility ends
and perceptibility begins, will have to be both visible and invisible their
objects, whether regarded in general or at the same time; but this is
impossible.
This concludes our survey of the characteristics of the organs
of Sense-perception and their objects, whether regarded in general or in
relation to each organ. Of the remaining subjects, we must first consider
that of memory and remembering.
THE END
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