On the Soul
By Aristotle
Translated by J.A. Smith
Book I
I.1. HOLDING as we do that, while knowledge of any kind is a thing to be honoured and prized, one
kind of it may, either by reason of its greater exactness or of a higher dignity and greater
wonderfulness in its objects, be more honourable and precious than another, on both accounts we
should naturally be led to place in the front rank the study of the soul. The knowledge of the soul
admittedly contributes greatly to the advance of truth in general, and, above all, to our
understanding of Nature, for the soul is in some sense the principle of animal life. Our aim is to
grasp and understand, first its essential nature, and secondly its properties; of these some are
taught to be affections proper to the soul itself, while others are considered to attach to the
animal owing to the presence within it of soul.
To attain any assured knowledge about the soul is one of the most difficult things in the world.
As the form of question which here presents itself, viz. the question 'What is it?', recurs in other
fields, it might be supposed that there was some single method of inquiry applicable to all objects
whose essential nature (as we are endeavouring to ascertain there is for derived properties the
single method of demonstration); in that case what we should have to seek for would be this unique
method. But if there is no such single and general method for solving the question of essence, our
task becomes still more difficult; in the case of each different subject we shall have to determine
the appropriate process of investigation. If to this there be a clear answer, e.g. that the process
is demonstration or division, or some known method, difficulties and hesitations still beset us-with
what facts shall we begin the inquiry? For the facts which form the starting-points in different
subjects must be different, as e.g. in the case of numbers and surfaces.
First, no doubt, it is necessary to determine in which of the summa genera soul lies, what it is;
is it 'a this-somewhat, 'a substance, or is it a quale or a quantum, or some other of the remaining
kinds of predicates which we have distinguished? Further, does soul belong to the class of potential
existents, or is it not rather an actuality? Our answer to this question is of the greatest
importance.
We must consider also whether soul is divisible or is without parts, and whether it is everywhere
homogeneous or not; and if not homogeneous, whether its various forms are different specifically or
generically: up to the present time those who have discussed and investigated soul seem to have
confined themselves to the human soul. We must be careful not to ignore the question whether soul
can be defined in a single unambiguous formula, as is the case with animal, or whether we must not
give a separate formula for each of it, as we do for horse, dog, man, god (in the latter case the
'universal' animal-and so too every other 'common predicate'-being treated either as nothing at all
or as a later product). Further, if what exists is not a plurality of souls, but a plurality of
parts of one soul, which ought we to investigate first, the whole soul or its parts? (It is also a
difficult problem to decide which of these parts are in nature distinct from one another.) Again,
which ought we to investigate first, these parts or their functions, mind or thinking, the faculty
or the act of sensation, and so on? If the investigation of the functions precedes that of the
parts, the further question suggests itself: ought we not before either to consider the correlative
objects, e.g. of sense or thought? It seems not only useful for the discovery of the causes of the
derived properties of substances to be acquainted with the essential nature of those substances (as
in mathematics it is useful for the understanding of the property of the equality of the interior
angles of a triangle to two right angles to know the essential nature of the straight and the curved
or of the line and the plane) but also conversely, for the knowledge of the essential nature of a
substance is largely promoted by an acquaintance with its properties: for, when we are able to give
an account conformable to experience of all or most of the properties of a substance, we shall be in
the most favourable position to say something worth saying about the essential nature of that
subject; in all demonstration a definition of the essence is required as a starting-point, so that
definitions which do not enable us to discover the derived properties, or which fail to facilitate
even a conjecture about them, must obviously, one and all, be dialectical and futile.
A further problem presented by the affections of soul is this: are they all affections of the
complex of body and soul, or is there any one among them peculiar to the soul by itself? To
determine this is indispensable but difficult. If we consider the majority of them, there seems to
be no case in which the soul can act or be acted upon without involving the body; e.g. anger,
courage, appetite, and sensation generally. Thinking seems the most probable exception; but if this
too proves to be a form of imagination or to be impossible without imagination, it too requires a
body as a condition of its existence. If there is any way of acting or being acted upon proper to
soul, soul will be capable of separate existence; if there is none, its separate existence is
impossible. In the latter case, it will be like what is straight, which has many properties arising
from the straightness in it, e.g. that of touching a bronze sphere at a point, though straightness
divorced from the other constituents of the straight thing cannot touch it in this way; it cannot be
so divorced at all, since it is always found in a body. It therefore seems that all the affections
of soul involve a body-passion, gentleness, fear, pity, courage, joy, loving, and hating; in all
these there is a concurrent affection of the body. In support of this we may point to the fact that,
while sometimes on the occasion of violent and striking occurrences there is no excitement or fear
felt, on others faint and feeble stimulations produce these emotions, viz. when the body is already
in a state of tension resembling its condition when we are angry. Here is a still clearer case: in
the absence of any external cause of terror we find ourselves experiencing the feelings of a man in
terror. From all this it is obvious that the affections of soul are enmattered formulable essences.
Consequently their definitions ought to correspond, e.g. anger should be defined as a certain
mode of movement of such and such a body (or part or faculty of a body) by this or that cause and
for this or that end. That is precisely why the study of the soul must fall within the science of
Nature, at least so far as in its affections it manifests this double character. Hence a physicist
would define an affection of soul differently from a dialectician; the latter would define e.g.
anger as the appetite for returning pain for pain, or something like that, while the former would
define it as a boiling of the blood or warm substance surround the heart. The latter assigns the
material conditions, the former the form or formulable essence; for what he states is the formulable
essence of the fact, though for its actual existence there must be embodiment of it in a material
such as is described by the other. Thus the essence of a house is assigned in such a formula as 'a
shelter against destruction by wind, rain, and heat'; the physicist would describe it as 'stones,
bricks, and timbers'; but there is a third possible description which would say that it was that
form in that material with that purpose or end. Which, then, among these is entitled to be regarded
as the genuine physicist? The one who confines himself to the material, or the one who restricts
himself to the formulable essence alone? Is it not rather the one who combines both in a single
formula? If this is so, how are we to characterize the other two? Must we not say that there is no
type of thinker who concerns himself with those qualities or attributes of the material which are in
fact inseparable from the material, and without attempting even in thought to separate them? The
physicist is he who concerns himself with all the properties active and passive of bodies or
materials thus or thus defined; attributes not considered as being of this character he leaves to
others, in certain cases it may be to a specialist, e.g. a carpenter or a physician, in others (a)
where they are inseparable in fact, but are separable from any particular kind of body by an effort
of abstraction, to the mathematician, (b) where they are separate both in fact and in thought from
body altogether, to the First Philosopher or metaphysician. But we must return from this digression,
and repeat that the affections of soul are inseparable from the material substratum of animal life,
to which we have seen that such affections, e.g. passion and fear, attach, and have not the same
mode of being as a line or a plane.
I.2. For our study of soul it is necessary, while formulating the problems of which in our
further advance we are to find the solutions, to call into council the views of those of our
predecessors who have declared any opinion on this subject, in order that we may profit by whatever
is sound in their suggestions and avoid their errors.
The starting-point of our inquiry is an exposition of those characteristics which have chiefly
been held to belong to soul in its very nature. Two characteristic marks have above all others been
recognized as distinguishing that which has soul in it from that which has not-movement and
sensation. It may be said that these two are what our predecessors have fixed upon as characteristic
of soul.
Some say that what originates movement is both pre-eminently and primarily soul; believing that
what is not itself moved cannot originate movement in another, they arrived at the view that soul
belongs to the class of things in movement. This is what led Democritus to say that soul is a sort
of fire or hot substance; his 'forms' or atoms are infinite in number; those which are spherical he
calls fire and soul, and compares them to the motes in the air which we see in shafts of light
coming through windows; the mixture of seeds of all sorts he calls the elements of the whole of
Nature (Leucippus gives a similar account); the spherical atoms are identified with soul because
atoms of that shape are most adapted to permeate everywhere, and to set all the others moving by
being themselves in movement. This implies the view that soul is identical with what produces
movement in animals. That is why, further, they regard respiration as the characteristic mark of
life; as the environment compresses the bodies of animals, and tends to extrude those atoms which
impart movement to them, because they themselves are never at rest, there must be a reinforcement of
these by similar atoms coming in from without in the act of respiration; for they prevent the
extrusion of those which are already within by counteracting the compressing and consolidating force
of the environment; and animals continue to live only so long as they are able to maintain this
resistance.
The doctrine of the Pythagoreans seems to rest upon the same ideas; some of them declared the
motes in air, others what moved them, to be soul. These motes were referred to because they are seen
always in movement, even in a complete calm.
The same tendency is shown by those who define soul as that which moves itself; all seem to hold
the view that movement is what is closest to the nature of soul, and that while all else is moved by
soul, it alone moves itself. This belief arises from their never seeing anything originating
movement which is not first itself moved.
Similarly also Anaxagoras (and whoever agrees with him in saying that mind set the whole in
movement) declares the moving cause of things to be soul. His position must, however, be
distinguished from that of Democritus. Democritus roundly identifies soul and mind, for he
identifies what appears with what is true-that is why he commends Homer for the phrase 'Hector lay
with thought distraught'; he does not employ mind as a special faculty dealing with truth, but
identifies soul and mind. What Anaxagoras says about them is more obscure; in many places he tells
us that the cause of beauty and order is mind, elsewhere that it is soul; it is found, he says, in
all animals, great and small, high and low, but mind (in the sense of intelligence) appears not to
belong alike to all animals, and indeed not even to all human beings.
All those, then, who had special regard to the fact that what has soul in it is moved, adopted
the view that soul is to be identified with what is eminently originative of movement. All, on the
other hand, who looked to the fact that what has soul in it knows or perceives what is, identify
soul with the principle or principles of Nature, according as they admit several such principles or
one only. Thus Empedocles declares that it is formed out of all his elements, each of them also
being soul; his words are:
For 'tis by Earth we see Earth, by Water Water,
By Ether Ether divine, by Fire destructive Fire,
By Love Love, and Hate by cruel Hate.
In the same way Plato in the Timaeus fashions soul out of his elements; for like, he holds, is
known by like, and things are formed out of the principles or elements, so that soul must be so too.
Similarly also in his lectures 'On Philosophy' it was set forth that the Animal-itself is compounded
of the Idea itself of the One together with the primary length, breadth, and depth, everything else,
the objects of its perception, being similarly constituted. Again he puts his view in yet other
terms: Mind is the monad, science or knowledge the dyad (because it goes undeviatingly from one
point to another), opinion the number of the plane, sensation the number of the solid; the numbers
are by him expressly identified with the Forms themselves or principles, and are formed out of the
elements; now things are apprehended either by mind or science or opinion or sensation, and these
same numbers are the Forms of things.
Some thinkers, accepting both premisses, viz. that the soul is both originative of movement and
cognitive, have compounded it of both and declared the soul to be a self-moving number.
As to the nature and number of the first principles opinions differ. The difference is greatest
between those who regard them as corporeal and those who regard them as incorporeal, and from both
dissent those who make a blend and draw their principles from both sources. The number of principles
is also in dispute; some admit one only, others assert several. There is a consequent diversity in
their several accounts of soul; they assume, naturally enough, that what is in its own nature
originative of movement must be among what is primordial. That has led some to regard it as fire,
for fire is the subtlest of the elements and nearest to incorporeality; further, in the most primary
sense, fire both is moved and originates movement in all the others.
Democritus has expressed himself more ingeniously than the rest on the grounds for ascribing each
of these two characters to soul; soul and mind are, he says, one and the same thing, and this thing
must be one of the primary and indivisible bodies, and its power of originating movement must be due
to its fineness of grain and the shape of its atoms; he says that of all the shapes the spherical is
the most mobile, and that this is the shape of the particles of fire and mind.
Anaxagoras, as we said above, seems to distinguish between soul and mind, but in practice he
treats them as a single substance, except that it is mind that he specially posits as the principle
of all things; at any rate what he says is that mind alone of all that is simple, unmixed, and pure.
He assigns both characteristics, knowing and origination of movement, to the same principle, when he
says that it was mind that set the whole in movement.
Thales, too, to judge from what is recorded about him, seems to have held soul to be a motive
force, since he said that the magnet has a soul in it because it moves the iron.
Diogenes (and others) held the soul to be air because he believed air to be finest in grain and a
first principle; therein lay the grounds of the soul's powers of knowing and originating movement.
As the primordial principle from which all other things are derived, it is cognitive; as finest in
grain, it has the power to originate movement.
Heraclitus too says that the first principle-the 'warm exhalation' of which, according to him,
everything else is composed-is soul; further, that this exhalation is most incorporeal and in
ceaseless flux; that what is in movement requires that what knows it should be in movement; and that
all that is has its being essentially in movement (herein agreeing with the majority).
Alcmaeon also seems to have held a similar view about soul; he says that it is immortal because
it resembles 'the immortals,' and that this immortality belongs to it in virtue of its ceaseless
movement; for all the 'things divine,' moon, sun, the planets, and the whole heavens, are in
perpetual movement.
of More superficial writers, some, e.g. Hippo, have pronounced it to be water; they seem to have
argued from the fact that the seed of all animals is fluid, for Hippo tries to refute those who say
that the soul is blood, on the ground that the seed, which is the primordial soul, is not blood.
Another group (Critias, for example) did hold it to be blood; they take perception to be the most
characteristic attribute of soul, and hold that perceptiveness is due to the nature of blood.
Each of the elements has thus found its partisan, except earth-earth has found no supporter
unless we count as such those who have declared soul to be, or to be compounded of, all the
elements. All, then, it may be said, characterize the soul by three marks, Movement, Sensation,
Incorporeality, and each of these is traced back to the first principles. That is why (with one
exception) all those who define the soul by its power of knowing make it either an element or
constructed out of the elements. The language they all use is similar; like, they say, is known by
like; as the soul knows everything, they construct it out of all the principles. Hence all those who
admit but one cause or element, make the soul also one (e.g. fire or air), while those who admit a
multiplicity of principles make the soul also multiple. The exception is Anaxagoras; he alone says
that mind is impassible and has nothing in common with anything else. But, if this is so, how or in
virtue of what cause can it know? That Anaxagoras has not explained, nor can any answer be inferred
from his words. All who acknowledge pairs of opposites among their principles, construct the soul
also out of these contraries, while those who admit as principles only one contrary of each pair,
e.g. either hot or cold, likewise make the soul some one of these. That is why, also, they allow
themselves to be guided by the names; those who identify soul with the hot argue that sen (to live)
is derived from sein (to boil), while those who identify it with the cold say that soul (psuche) is
so called from the process of respiration and (katapsuxis). Such are the traditional opinions
concerning soul, together with the grounds on which they are maintained.
I.3. We must begin our examination with movement; for doubtless, not only is it false that the
essence of soul is correctly described by those who say that it is what moves (or is capable of
moving) itself, but it is an impossibility that movement should be even an attribute of it.
We have already pointed out that there is no necessity that what originates movement should
itself be moved. There are two senses in which anything may be moved-either (a) indirectly, owing to
something other than itself, or (b) directly, owing to itself. Things are 'indirectly moved' which
are moved as being contained in something which is moved, e.g. sailors in a ship, for they are moved
in a different sense from that in which the ship is moved; the ship is 'directly moved', they are
'indirectly moved', because they are in a moving vessel. This is clear if we consider their limbs;
the movement proper to the legs (and so to man) is walking, and in this case the sailors tare not
walking. Recognizing the double sense of 'being moved', what we have to consider now is whether the
soul is 'directly moved' and participates in such direct movement.
There are four species of movement-locomotion, alteration, diminution, growth; consequently if
the soul is moved, it must be moved with one or several or all of these species of movement. Now if
its movement is not incidental, there must be a movement natural to it, and, if so, as all the
species enumerated involve place, place must be natural to it. But if the essence of soul be to move
itself, its being moved cannot be incidental to-as it is to what is white or three cubits long; they
too can be moved, but only incidentally-what is moved is that of which 'white' and 'three cubits
long' are the attributes, the body in which they inhere; hence they have no place: but if the soul
naturally partakes in movement, it follows that it must have a place.
Further, if there be a movement natural to the soul, there must be a counter-movement unnatural
to it, and conversely. The same applies to rest as well as to movement; for the terminus ad quem of
a thing's natural movement is the place of its natural rest, and similarly the terminus ad quem of
its enforced movement is the place of its enforced rest. But what meaning can be attached to
enforced movements or rests of the soul, it is difficult even to imagine.
Further, if the natural movement of the soul be upward, the soul must be fire; if downward, it
must be earth; for upward and downward movements are the definitory characteristics of these bodies.
The same reasoning applies to the intermediate movements, termini, and bodies. Further, since the
soul is observed to originate movement in the body, it is reasonable to suppose that it transmits to
the body the movements by which it itself is moved, and so, reversing the order, we may infer from
the movements of the body back to similar movements of the soul. Now the body is moved from place to
place with movements of locomotion. Hence it would follow that the soul too must in accordance with
the body change either its place as a whole or the relative places of its parts. This carries with
it the possibility that the soul might even quit its body and re-enter it, and with this would be
involved the possibility of a resurrection of animals from the dead. But, it may be contended, the
soul can be moved indirectly by something else; for an animal can be pushed out of its course. Yes,
but that to whose essence belongs the power of being moved by itself, cannot be moved by something
else except incidentally, just as what is good by or in itself cannot owe its goodness to something
external to it or to some end to which it is a means.
If the soul is moved, the most probable view is that what moves it is sensible things.
We must note also that, if the soul moves itself, it must be the mover itself that is moved, so
that it follows that if movement is in every case a displacement of that which is in movement, in
that respect in which it is said to be moved, the movement of the soul must be a departure from its
essential nature, at least if its self-movement is essential to it, not incidental.
Some go so far as to hold that the movements which the soul imparts to the body in which it is
are the same in kind as those with which it itself is moved. An example of this is Democritus, who
uses language like that of the comic dramatist Philippus, who accounts for the movements that
Daedalus imparted to his wooden Aphrodite by saying that he poured quicksilver into it; similarly
Democritus says that the spherical atoms which according to him constitute soul, owing to their own
ceaseless movements draw the whole body after them and so produce its movements. We must urge the
question whether it is these very same atoms which produce rest also-how they could do so, it is
difficult and even impossible to say. And, in general, we may object that it is not in this way that
the soul appears to originate movement in animals-it is through intention or process of thinking.
It is in the same fashion that the Timaeus also tries to give a physical account of how the soul
moves its body; the soul, it is there said, is in movement, and so owing to their mutual implication
moves the body also. After compounding the soul-substance out of the elements and dividing it in
accordance with the harmonic numbers, in order that it may possess a connate sensibility for
'harmony' and that the whole may move in movements well attuned, the Demiurge bent the straight line
into a circle; this single circle he divided into two circles united at two common points; one of
these he subdivided into seven circles. All this implies that the movements of the soul are
identified with the local movements of the heavens.
Now, in the first place, it is a mistake to say that the soul is a spatial magnitude. It is
evident that Plato means the soul of the whole to be like the sort of soul which is called mind not
like the sensitive or the desiderative soul, for the movements of neither of these are circular. Now
mind is one and continuous in the sense in which the process of thinking is so, and thinking is
identical with the thoughts which are its parts; these have a serial unity like that of number, not
a unity like that of a spatial magnitude. Hence mind cannot have that kind of unity either; mind is
either without parts or is continuous in some other way than that which characterizes a spatial
magnitude. How, indeed, if it were a spatial magnitude, could mind possibly think? Will it think
with any one indifferently of its parts? In this case, the 'part' must be understood either in the
sense of a spatial magnitude or in the sense of a point (if a point can be called a part of a
spatial magnitude). If we accept the latter alternative, the points being infinite in number,
obviously the mind can never exhaustively traverse them; if the former, the mind must think the same
thing over and over again, indeed an infinite number of times (whereas it is manifestly possible to
think a thing once only). If contact of any part whatsoever of itself with the object is all that is
required, why need mind move in a circle, or indeed possess magnitude at all? On the other hand, if
contact with the whole circle is necessary, what meaning can be given to the contact of the parts?
Further, how could what has no parts think what has parts, or what has parts think what has none? We
must identify the circle referred to with mind; for it is mind whose movement is thinking, and it is
the circle whose movement is revolution, so that if thinking is a movement of revolution, the circle
which has this characteristic movement must be mind.
If the circular movement is eternal, there must be something which mind is always thinking-what
can this be? For all practical processes of thinking have limits-they all go on for the sake of
something outside the process, and all theoretical processes come to a close in the same way as the
phrases in speech which express processes and results of thinking. Every such linguistic phrase is
either definitory or demonstrative. Demonstration has both a starting-point and may be said to end
in a conclusion or inferred result; even if the process never reaches final completion, at any rate
it never returns upon itself again to its starting-point, it goes on assuming a fresh middle term or
a fresh extreme, and moves straight forward, but circular movement returns to its starting-point.
Definitions, too, are closed groups of terms.
Further, if the same revolution is repeated, mind must repeatedly think the same object.
Further, thinking has more resemblance to a coming to rest or arrest than to a movement; the same
may be said of inferring.
It might also be urged that what is difficult and enforced is incompatible with blessedness; if
the movement of the soul is not of its essence, movement of the soul must be contrary to its nature.
It must also be painful for the soul to be inextricably bound up with the body; nay more, if, as is
frequently said and widely accepted, it is better for mind not to be embodied, the union must be for
it undesirable.
Further, the cause of the revolution of the heavens is left obscure. It is not the essence of
soul which is the cause of this circular movement-that movement is only incidental to soul-nor is, a
fortiori, the body its cause. Again, it is not even asserted that it is better that soul should be
so moved; and yet the reason for which God caused the soul to move in a circle can only have been
that movement was better for it than rest, and movement of this kind better than any other. But
since this sort of consideration is more appropriate to another field of speculation, let us dismiss
it for the present.
The view we have just been examining, in company with most theories about the soul, involves the
following absurdity: they all join the soul to a body, or place it in a body, without adding any
specification of the reason of their union, or of the bodily conditions required for it. Yet such
explanation can scarcely be omitted; for some community of nature is presupposed by the fact that
the one acts and the other is acted upon, the one moves and the other is moved; interaction always
implies a special nature in the two interagents. All, however, that these thinkers do is to describe
the specific characteristics of the soul; they do not try to determine anything about the body which
is to contain it, as if it were possible, as in the Pythagorean myths, that any soul could be
clothed upon with any body-an absurd view, for each body seems to have a form and shape of its own.
It is as absurd as to say that the art of carpentry could embody itself in flutes; each art must use
its tools, each soul its body.
I.4. There is yet another theory about soul, which has commended itself to many as no less
probable than any of those we have hitherto mentioned, and has rendered public account of itself in
the court of popular discussion. Its supporters say that the soul is a kind of harmony, for (a)
harmony is a blend or composition of contraries, and (b) the body is compounded out of contraries.
Harmony, however, is a certain proportion or composition of the constituents blended, and soul can
be neither the one nor the other of these. Further, the power of originating movement cannot belong
to a harmony, while almost all concur in regarding this as a principal attribute of soul. It is more
appropriate to call health (or generally one of the good states of the body) a harmony than to
predicate it of the soul. The absurdity becomes most apparent when we try to attribute the active
and passive affections of the soul to a harmony; the necessary readjustment of their conceptions is
difficult. Further, in using the word 'harmony' we have one or other of two cases in our mind; the
most proper sense is in relation to spatial magnitudes which have motion and position, where harmony
means the disposition and cohesion of their parts in such a manner as to prevent the introduction
into the whole of anything homogeneous with it, and the secondary sense, derived from the former, is
that in which it means the ratio between the constituents so blended; in neither of these senses is
it plausible to predicate it of soul. That soul is a harmony in the sense of the mode of composition
of the parts of the body is a view easily refutable; for there are many composite parts and those
variously compounded; of what bodily part is mind or the sensitive or the appetitive faculty the
mode of composition? And what is the mode of composition which constitutes each of them? It is
equally absurd to identify the soul with the ratio of the mixture; for the mixture which makes flesh
has a different ratio between the elements from that which makes bone. The consequence of this view
will therefore be that distributed throughout the whole body there will be many souls, since every
one of the bodily parts is a different mixture of the elements, and the ratio of mixture is in each
case a harmony, i.e. a soul.
From Empedocles at any rate we might demand an answer to the following question for he says that
each of the parts of the body is what it is in virtue of a ratio between the elements: is the soul
identical with this ratio, or is it not rather something over and above this which is formed in the
parts? Is love the cause of any and every mixture, or only of those that are in the right ratio? Is
love this ratio itself, or is love something over and above this? Such are the problems raised by
this account. But, on the other hand, if the soul is different from the mixture, why does it
disappear at one and the same moment with that relation between the elements which constitutes flesh
or the other parts of the animal body? Further, if the soul is not identical with the ratio of
mixture, and it is consequently not the case that each of the parts has a soul, what is that which
perishes when the soul quits the body?
That the soul cannot either be a harmony, or be moved in a circle, is clear from what we have
said. Yet that it can be moved incidentally is, as we said above, possible, and even that in a sense
it can move itself, i.e. in the sense that the vehicle in which it is can be moved, and moved by it;
in no other sense can the soul be moved in space.
More legitimate doubts might remain as to its movement in view of the following facts. We speak
of the soul as being pained or pleased, being bold or fearful, being angry, perceiving, thinking.
All these are regarded as modes of movement, and hence it might be inferred that the soul is moved.
This, however, does not necessarily follow. We may admit to the full that being pained or pleased,
or thinking, are movements (each of them a 'being moved'), and that the movement is originated by
the soul. For example we may regard anger or fear as such and such movements of the heart, and
thinking as such and such another movement of that organ, or of some other; these modifications may
arise either from changes of place in certain parts or from qualitative alterations (the special
nature of the parts and the special modes of their changes being for our present purpose
irrelevant). Yet to say that it is the soul which is angry is as inexact as it would be to say that
it is the soul that weaves webs or builds houses. It is doubtless better to avoid saying that the
soul pities or learns or thinks and rather to say that it is the man who does this with his soul.
What we mean is not that the movement is in the soul, but that sometimes it terminates in the soul
and sometimes starts from it, sensation e.g. coming from without inwards, and reminiscence starting
from the soul and terminating with the movements, actual or residual, in the sense organs.
The case of mind is different; it seems to be an independent substance implanted within the soul
and to be incapable of being destroyed. If it could be destroyed at all, it would be under the
blunting influence of old age. What really happens in respect of mind in old age is, however,
exactly parallel to what happens in the case of the sense organs; if the old man could recover the
proper kind of eye, he would see just as well as the young man. The incapacity of old age is due to
an affection not of the soul but of its vehicle, as occurs in drunkenness or disease. Thus it is
that in old age the activity of mind or intellectual apprehension declines only through the decay of
some other inward part; mind itself is impassible. Thinking, loving, and hating are affections not
of mind, but of that which has mind, so far as it has it. That is why, when this vehicle decays,
memory and love cease; they were activities not of mind, but of the composite which has perished;
mind is, no doubt, something more divine and impassible. That the soul cannot be moved is therefore
clear from what we have said, and if it cannot be moved at all, manifestly it cannot be moved by
itself.
Of all the opinions we have enumerated, by far the most unreasonable is that which declares the
soul to be a self-moving number; it involves in the first place all the impossibilities which follow
from regarding the soul as moved, and in the second special absurdities which follow from calling it
a number. How we to imagine a unit being moved? By what agency? What sort of movement can be
attributed to what is without parts or internal differences? If the unit is both originative of
movement and itself capable of being moved, it must contain difference.
Further, since they say a moving line generates a surface and a moving point a line, the
movements of the psychic units must be lines (for a point is a unit having position, and the number
of the soul is, of course, somewhere and has position).
Again, if from a number a number or a unit is subtracted, the remainder is another number; but
plants and many animals when divided continue to live, and each segment is thought to retain the
same kind of soul.
It must be all the same whether we speak of units or corpuscles; for if the spherical atoms of
Democritus became points, nothing being retained but their being a quantum, there must remain in
each a moving and a moved part, just as there is in what is continuous; what happens has nothing to
do with the size of the atoms, it depends solely upon their being a quantum. That is why there must
be something to originate movement in the units. If in the animal what originates movement is the
soul, so also must it be in the case of the number, so that not the mover and the moved together,
but the mover only, will be the soul. But how is it possible for one of the units to fulfil this
function of originating movement? There must be some difference between such a unit and all the
other units, and what difference can there be between one placed unit and another except a
difference of position? If then, on the other hand, these psychic units within the body are
different from the points of the body, there will be two sets of units both occupying the same
place; for each unit will occupy a point. And yet, if there can be two, why cannot there be an
infinite number? For if things can occupy an indivisible lace, they must themselves be indivisible.
If, on the other hand, the points of the body are identical with the units whose number is the soul,
or if the number of the points in the body is the soul, why have not all bodies souls? For all
bodies contain points or an infinity of points.
Further, how is it possible for these points to be isolated or separated from their bodies,
seeing that lines cannot be resolved into points?
I.5. The result is, as we have said, that this view, while on the one side identical with that of
those who maintain that soul is a subtle kind of body, is on the other entangled in the absurdity
peculiar to Democritus' way of describing the manner in which movement is originated by soul. For if
the soul is present throughout the whole percipient body, there must, if the soul be a kind of body,
be two bodies in the same place; and for those who call it a number, there must be many points at
one point, or every body must have a soul, unless the soul be a different sort of number-other, that
is, than the sum of the points existing in a body. Another consequence that follows is that the
animal must be moved by its number precisely in the way that Democritus explained its being moved by
his spherical psychic atoms. What difference does it make whether we speak of small spheres or of
large units, or, quite simply, of units in movement? One way or another, the movements of the animal
must be due to their movements. Hence those who combine movement and number in the same subject lay
themselves open to these and many other similar absurdities. It is impossible not only that these
characters should give the definition of soul-it is impossible that they should even be attributes
of it. The point is clear if the attempt be made to start from this as the account of soul and
explain from it the affections and actions of the soul, e.g. reasoning, sensation, pleasure, pain,
etc. For, to repeat what we have said earlier, movement and number do not facilitate even conjecture
about the derivative properties of soul.
Such are the three ways in which soul has traditionally been defined; one group of thinkers
declared it to be that which is most originative of movement because it moves itself, another group
to be the subtlest and most nearly incorporeal of all kinds of body. We have now sufficiently set
forth the difficulties and inconsistencies to which these theories are exposed. It remains now to
examine the doctrine that soul is composed of the elements.
The reason assigned for this doctrine is that thus the soul may perceive or come to know
everything that is, but the theory necessarily involves itself in many impossibilities. Its
upholders assume that like is known only by like, and imagine that by declaring the soul to be
composed of the elements they succeed in identifying the soul with all the things it is capable of
apprehending. But the elements are not the only things it knows; there are many others, or, more
exactly, an infinite number of others, formed out of the elements. Let us admit that the soul knows
or perceives the elements out of which each of these composites is made up; but by what means will
it know or perceive the composite whole, e.g. what God, man, flesh, bone (or any other compound) is?
For each is, not merely the elements of which it is composed, but those elements combined in a
determinate mode or ratio, as Empedocles himself says of bone,
The kindly Earth in its broad-bosomed moulds
Won of clear Water two parts out of eight,
And four of Fire; and so white bones were formed.
Nothing, therefore, will be gained by the presence of the elements in the soul, unless there be
also present there the various formulae of proportion and the various compositions in accordance
with them. Each element will indeed know its fellow outside, but there will be no knowledge of bone
or man, unless they too are present in the constitution of the soul. The impossibility of this needs
no pointing out; for who would suggest that stone or man could enter into the constitution of the
soul? The same applies to 'the good' and 'the not-good', and so on.
Further, the word 'is' has many meanings: it may be used of a 'this' or substance, or of a
quantum, or of a quale, or of any other of the kinds of predicates we have distinguished. Does the
soul consist of all of these or not? It does not appear that all have common elements. Is the soul
formed out of those elements alone which enter into substances? so how will it be able to know each
of the other kinds of thing? Will it be said that each kind of thing has elements or principles of
its own, and that the soul is formed out of the whole of these? In that case, the soul must be a
quantum and a quale and a substance. But all that can be made out of the elements of a quantum is a
quantum, not a substance. These (and others like them) are the consequences of the view that the
soul is composed of all the elements.
It is absurd, also, to say both (a) that like is not capable of being affected by like, and (b)
that like is perceived or known by like, for perceiving, and also both thinking and knowing, are, on
their own assumption, ways of being affected or moved.
There are many puzzles and difficulties raised by saying, as Empedocles does, that each set of
things is known by means of its corporeal elements and by reference to something in soul which is
like them, and additional testimony is furnished by this new consideration; for all the parts of the
animal body which consist wholly of earth such as bones, sinews, and hair seem to be wholly
insensitive and consequently not perceptive even of objects earthy like themselves, as they ought to
have been.
Further, each of the principles will have far more ignorance than knowledge, for though each of
them will know one thing, there will be many of which it will be ignorant. Empedocles at any rate
must conclude that his God is the least intelligent of all beings, for of him alone is it true that
there is one thing, Strife, which he does not know, while there is nothing which mortal beings do
not know, for ere is nothing which does not enter into their composition.
In general, we may ask, Why has not everything a soul, since everything either is an element, or
is formed out of one or several or all of the elements? Each must certainly know one or several or
all.
The problem might also be raised, What is that which unifies the elements into a soul? The
elements correspond, it would appear, to the matter; what unites them, whatever it is, is the
supremely important factor. But it is impossible that there should be something superior to, and
dominant over, the soul (and a fortiori over the mind); it is reasonable to hold that mind is by
nature most primordial and dominant, while their statement that it is the elements which are first
of all that is.
All, both those who assert that the soul, because of its knowledge or perception of what is
compounded out of the elements, and is those who assert that it is of all things the most
originative of movement, fail to take into consideration all kinds of soul. In fact (1) not all
beings that perceive can originate movement; there appear to be certain animals which stationary,
and yet local movement is the only one, so it seems, which the soul originates in animals. And (2)
the same object-on holds against all those who construct mind and the perceptive faculty out of the
elements; for it appears that plants live, and yet are not endowed with locomotion or perception,
while a large number of animals are without discourse of reason. Even if these points were waived
and mind admitted to be a part of the soul (and so too the perceptive faculty), still, even so,
there would be kinds and parts of soul of which they had failed to give any account.
The same objection lies against the view expressed in the 'Orphic' poems: there it is said that
the soul comes in from the whole when breathing takes place, being borne in upon the winds. Now this
cannot take place in the case of plants, nor indeed in the case of certain classes of animal, for
not all classes of animal breathe. This fact has escaped the notice of the holders of this view.
If we must construct the soul out of the elements, there is no necessity to suppose that all the
elements enter into its construction; one element in each pair of contraries will suffice to enable
it to know both that element itself and its contrary. By means of the straight line we know both
itself and the curved-the carpenter's rule enables us to test both-but what is curved does not
enable us to distinguish either itself or the straight. Certain thinkers say that soul is
intermingled in the whole universe, and it is perhaps for that reason that Thales came to the
opinion that all things are full of gods. This presents some difficulties: Why does the soul when it
resides in air or fire not form an animal, while it does so when it resides in mixtures of the
elements, and that although it is held to be of higher quality when contained in the former? (One
might add the question, why the soul in air is maintained to be higher and more immortal than that
in animals.) Both possible ways of replying to the former question lead to absurdity or paradox; for
it is beyond paradox to say that fire or air is an animal, and it is absurd to refuse the name of
animal to what has soul in it. The opinion that the elements have soul in them seems to have arisen
from the doctrine that a whole must be homogeneous with its parts. If it is true that animals become
animate by drawing into themselves a portion of what surrounds them, the partisans of this view are
bound to say that the soul of the Whole too is homogeneous with all its parts. If the air sucked in
is homogeneous, but soul heterogeneous, clearly while some part of soul will exist in the inbreathed
air, some other part will not. The soul must either be homogeneous, or such that there are some
parts of the Whole in which it is not to be found.
From what has been said it is now clear that knowing as an attribute of soul cannot be explained
by soul's being composed of the elements, and that it is neither sound nor true to speak of soul as
moved. But since (a) knowing, perceiving, opining, and further (b) desiring, wishing, and generally
all other modes of appetition, belong to soul, and (c) the local movements of animals, and (d)
growth, maturity, and decay are produced by the soul, we must ask whether each of these is an
attribute of the soul as a whole, i.e. whether it is with the whole soul we think, perceive, move
ourselves, act or are acted upon, or whether each of them requires a different part of the soul? So
too with regard to life. Does it depend on one of the parts of soul? Or is it dependent on more than
one? Or on all? Or has it some quite other cause?
Some hold that the soul is divisible, and that one part thinks, another desires. If, then, its
nature admits of its being divided, what can it be that holds the parts together? Surely not the
body; on the contrary it seems rather to be the soul that holds the body together; at any rate when
the soul departs the body disintegrates and decays. If, then, there is something else which makes
the soul one, this unifying agency would have the best right to the name of soul, and we shall have
to repeat for it the question: Is it one or multipartite? If it is one, why not at once admit that
'the soul' is one? If it has parts, once more the question must be put: What holds its parts
together, and so ad infinitum?
The question might also be raised about the parts of the soul: What is the separate role of each
in relation to the body? For, if the whole soul holds together the whole body, we should expect each
part of the soul to hold together a part of the body. But this seems an impossibility; it is
difficult even to imagine what sort of bodily part mind will hold together, or how it will do this.
It is a fact of observation that plants and certain insects go on living when divided into
segments; this means that each of the segments has a soul in it identical in species, though not
numerically identical in the different segments, for both of the segments for a time possess the
power of sensation and local movement. That this does not last is not surprising, for they no longer
possess the organs necessary for self-maintenance. But, all the same, in each of the bodily parts
there are present all the parts of soul, and the souls so present are homogeneous with one another
and with the whole; this means that the several parts of the soul are indisseverable from one
another, although the whole soul is divisible. It seems also that the principle found in plants is
also a kind of soul; for this is the only principle which is common to both animals and plants; and
this exists in isolation from the principle of sensation, though there nothing which has the latter
without the former.
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Book II
II.1. LET the foregoing suffice as our account of the views concerning the soul which have been
handed on by our predecessors; let us now dismiss them and make as it were a completely fresh start,
endeavouring to give a precise answer to the question, What is soul? i.e. to formulate the most
general possible definition of it.
We are in the habit of recognizing, as one determinate kind of what is, substance, and that in
several senses, (a) in the sense of matter or that which in itself is not 'a this', and (b) in the
sense of form or essence, which is that precisely in virtue of which a thing is called 'a this', and
thirdly (c) in the sense of that which is compounded of both (a) and (b). Now matter is
potentiality, form actuality; of the latter there are two grades related to one another as e.g.
knowledge to the exercise of knowledge.
Among substances are by general consent reckoned bodies and especially natural bodies; for they
are the principles of all other bodies. Of natural bodies some have life in them, others not; by
life we mean self-nutrition and growth (with its correlative decay). It follows that every natural
body which has life in it is a substance in the sense of a composite.
But since it is also a body of such and such a kind, viz. having life, the body cannot be soul;
the body is the subject or matter, not what is attributed to it. Hence the soul must be a substance
in the sense of the form of a natural body having life potentially within it. But substance is
actuality, and thus soul is the actuality of a body as above characterized. Now the word actuality
has two senses corresponding respectively to the possession of knowledge and the actual exercise of
knowledge. It is obvious that the soul is actuality in the first sense, viz. that of knowledge as
possessed, for both sleeping and waking presuppose the existence of soul, and of these waking
corresponds to actual knowing, sleeping to knowledge possessed but not employed, and, in the history
of the individual, knowledge comes before its employment or exercise.
That is why the soul is the first grade of actuality of a natural body having life potentially in
it. The body so described is a body which is organized. The parts of plants in spite of their
extreme simplicity are 'organs'; e.g. the leaf serves to shelter the pericarp, the pericarp to
shelter the fruit, while the roots of plants are analogous to the mouth of animals, both serving for
the absorption of food. If, then, we have to give a general formula applicable to all kinds of soul,
we must describe it as the first grade of actuality of a natural organized body. That is why we can
wholly dismiss as unnecessary the question whether the soul and the body are one: it is as
meaningless as to ask whether the wax and the shape given to it by the stamp are one, or generally
the matter of a thing and that of which it is the matter. Unity has many senses (as many as 'is'
has), but the most proper and fundamental sense of both is the relation of an actuality to that of
which it is the actuality. We have now given an answer to the question, What is soul?-an answer
which applies to it in its full extent. It is substance in the sense which corresponds to the
definitive formula of a thing's essence. That means that it is 'the essential whatness' of a body of
the character just assigned. Suppose that what is literally an 'organ', like an axe, were a natural
body, its 'essential whatness', would have been its essence, and so its soul; if this disappeared
from it, it would have ceased to be an axe, except in name. As it is, it is just an axe; it wants
the character which is required to make its whatness or formulable essence a soul; for that, it
would have had to be a natural body of a particular kind, viz. one having in itself the power of
setting itself in movement and arresting itself. Next, apply this doctrine in the case of the
'parts' of the living body. Suppose that the eye were an animal-sight would have been its soul, for
sight is the substance or essence of the eye which corresponds to the formula, the eye being merely
the matter of seeing; when seeing is removed the eye is no longer an eye, except in name-it is no
more a real eye than the eye of a statue or of a painted figure. We must now extend our
consideration from the 'parts' to the whole living body; for what the departmental sense is to the
bodily part which is its organ, that the whole faculty of sense is to the whole sensitive body as
such.
We must not understand by that which is 'potentially capable of living' what has lost the soul it
had, but only what still retains it; but seeds and fruits are bodies which possess the
qualification. Consequently, while waking is actuality in a sense corresponding to the cutting and
the seeing, the soul is actuality in the sense corresponding to the power of sight and the power in
the tool; the body corresponds to what exists in potentiality; as the pupil plus the power of sight
constitutes the eye, so the soul plus the body constitutes the animal.
From this it indubitably follows that the soul is inseparable from its body, or at any rate that
certain parts of it are (if it has parts) for the actuality of some of them is nothing but the
actualities of their bodily parts. Yet some may be separable because they are not the actualities of
any body at all. Further, we have no light on the problem whether the soul may not be the actuality
of its body in the sense in which the sailor is the actuality of the ship.
This must suffice as our sketch or outline determination of the nature of soul.
II.2. Since what is clear or logically more evident emerges from what in itself is confused but
more observable by us, we must reconsider our results from this point of view. For it is not enough
for a definitive formula to express as most now do the mere fact; it must include and exhibit the
ground also. At present definitions are given in a form analogous to the conclusion of a syllogism;
e.g. What is squaring? The construction of an equilateral rectangle equal to a given oblong
rectangle. Such a definition is in form equivalent to a conclusion. One that tells us that squaring
is the discovery of a line which is a mean proportional between the two unequal sides of the given
rectangle discloses the ground of what is defined.
We resume our inquiry from a fresh starting-point by calling attention to the fact that what has
soul in it differs from what has not, in that the former displays life. Now this word has more than
one sense, and provided any one alone of these is found in a thing we say that thing is living.
Living, that is, may mean thinking or perception or local movement and rest, or movement in the
sense of nutrition, decay and growth. Hence we think of plants also as living, for they are observed
to possess in themselves an originative power through which they increase or decrease in all spatial
directions; they grow up and down, and everything that grows increases its bulk alike in both
directions or indeed in all, and continues to live so long as it can absorb nutriment.
This power of self-nutrition can be isolated from the other powers mentioned, but not they from
it-in mortal beings at least. The fact is obvious in plants; for it is the only psychic power they
possess.
This is the originative power the possession of which leads us to speak of things as living at
all, but it is the possession of sensation that leads us for the first time to speak of living
things as animals; for even those beings which possess no power of local movement but do possess the
power of sensation we call animals and not merely living things.
The primary form of sense is touch, which belongs to all animals. just as the power of
self-nutrition can be isolated from touch and sensation generally, so touch can be isolated from all
other forms of sense. (By the power of self-nutrition we mean that departmental power of the soul
which is common to plants and animals: all animals whatsoever are observed to have the sense of
touch.) What the explanation of these two facts is, we must discuss later. At present we must
confine ourselves to saying that soul is the source of these phenomena and is characterized by them,
viz. by the powers of self-nutrition, sensation, thinking, and motivity.
Is each of these a soul or a part of a soul? And if a part, a part in what sense? A part merely
distinguishable by definition or a part distinct in local situation as well? In the case of certain
of these powers, the answers to these questions are easy, in the case of others we are puzzled what
to say. just as in the case of plants which when divided are observed to continue to live though
removed to a distance from one another (thus showing that in their case the soul of each individual
plant before division was actually one, potentially many), so we notice a similar result in other
varieties of soul, i.e. in insects which have been cut in two; each of the segments possesses both
sensation and local movement; and if sensation, necessarily also imagination and appetition; for,
where there is sensation, there is also pleasure and pain, and, where these, necessarily also
desire.
We have no evidence as yet about mind or the power to think; it seems to be a widely different
kind of soul, differing as what is eternal from what is perishable; it alone is capable of existence
in isolation from all other psychic powers. All the other parts of soul, it is evident from what we
have said, are, in spite of certain statements to the contrary, incapable of separate existence
though, of course, distinguishable by definition. If opining is distinct from perceiving, to be
capable of opining and to be capable of perceiving must be distinct, and so with all the other forms
of living above enumerated. Further, some animals possess all these parts of soul, some certain of
them only, others one only (this is what enables us to classify animals); the cause must be
considered later.' A similar arrangement is found also within the field of the senses; some classes
of animals have all the senses, some only certain of them, others only one, the most indispensable,
touch.
Since the expression 'that whereby we live and perceive' has two meanings, just like the
expression 'that whereby we know'-that may mean either (a) knowledge or (b) the soul, for we can
speak of knowing by or with either, and similarly that whereby we are in health may be either (a)
health or (b) the body or some part of the body; and since of the two terms thus contrasted
knowledge or health is the name of a form, essence, or ratio, or if we so express it an actuality of
a recipient matter-knowledge of what is capable of knowing, health of what is capable of being made
healthy (for the operation of that which is capable of originating change terminates and has its
seat in what is changed or altered); further, since it is the soul by or with which primarily we
live, perceive, and think:-it follows that the soul must be a ratio or formulable essence, not a
matter or subject. For, as we said, word substance has three meanings form, matter, and the complex
of both and of these three what is called matter is potentiality, what is called form actuality.
Since then the complex here is the living thing, the body cannot be the actuality of the soul; it is
the soul which is the actuality of a certain kind of body. Hence the rightness of the view that the
soul cannot be without a body, while it csnnot he a body; it is not a body but something relative to
a body. That is why it is in a body, and a body of a definite kind. It was a mistake, therefore, to
do as former thinkers did, merely to fit it into a body without adding a definite specification of
the kind or character of that body. Reflection confirms the observed fact; the actuality of any
given thing can only be realized in what is already potentially that thing, i.e. in a matter of its
own appropriate to it. From all this it follows that soul is an actuality or formulable essence of
something that possesses a potentiality of being besouled.
II.3. Of the psychic powers above enumerated some kinds of living things, as we have said,
possess all, some less than all, others one only. Those we have mentioned are the nutritive, the
appetitive, the sensory, the locomotive, and the power of thinking. Plants have none but the first,
the nutritive, while another order of living things has this plus the sensory. If any order of
living things has the sensory, it must also have the appetitive; for appetite is the genus of which
desire, passion, and wish are the species; now all animals have one sense at least, viz. touch, and
whatever has a sense has the capacity for pleasure and pain and therefore has pleasant and painful
objects present to it, and wherever these are present, there is desire, for desire is just
appetition of what is pleasant. Further, all animals have the sense for food (for touch is the sense
for food); the food of all living things consists of what is dry, moist, hot, cold, and these are
the qualities apprehended by touch; all other sensible qualities are apprehended by touch only
indirectly. Sounds, colours, and odours contribute nothing to nutriment; flavours fall within the
field of tangible qualities. Hunger and thirst are forms of desire, hunger a desire for what is dry
and hot, thirst a desire for what is cold and moist; flavour is a sort of seasoning added to both.
We must later clear up these points, but at present it may be enough to say that all animals that
possess the sense of touch have also appetition. The case of imagination is obscure; we must examine
it later. Certain kinds of animals possess in addition the power of locomotion, and still another
order of animate beings, i.e. man and possibly another order like man or superior to him, the power
of thinking, i.e. mind. It is now evident that a single definition can be given of soul only in the
same sense as one can be given of figure. For, as in that case there is no figure distinguishable
and apart from triangle, etc., so here there is no soul apart from the forms of soul just
enumerated. It is true that a highly general definition can be given for figure which will fit all
figures without expressing the peculiar nature of any figure. So here in the case of soul and its
specific forms. Hence it is absurd in this and similar cases to demand an absolutely general
definition which will fail to express the peculiar nature of anything that is, or again, omitting
this, to look for separate definitions corresponding to each infima species. The cases of figure and
soul are exactly parallel; for the particulars subsumed under the common name in both cases-figures
and living beings-constitute a series, each successive term of which potentially contains its
predecessor, e.g. the square the triangle, the sensory power the self-nutritive. Hence we must ask
in the case of each order of living things, What is its soul, i.e. What is the soul of plant,
animal, man? Why the terms are related in this serial way must form the subject of later
examination. But the facts are that the power of perception is never found apart from the power of
self-nutrition, while-in plants-the latter is found isolated from the former. Again, no sense is
found apart from that of touch, while touch is found by itself; many animals have neither sight,
hearing, nor smell. Again, among living things that possess sense some have the power of locomotion,
some not. Lastly, certain living beings-a small minority-possess calculation and thought, for (among
mortal beings) those which possess calculation have all the other powers above mentioned, while the
converse does not hold-indeed some live by imagination alone, while others have not even
imagination. The mind that knows with immediate intuition presents a different problem.
It is evident that the way to give the most adequate definition of soul is to seek in the case of
each of its forms for the most appropriate definition.
II.4. It is necessary for the student of these forms of soul first to find a definition of each,
expressive of what it is, and then to investigate its derivative properties, etc. But if we are to
express what each is, viz. what the thinking power is, or the perceptive, or the nutritive, we must
go farther back and first give an account of thinking or perceiving, for in the order of
investigation the question of what an agent does precedes the question, what enables it to do what
it does. If this is correct, we must on the same ground go yet another step farther back and have
some clear view of the objects of each; thus we must start with these objects, e.g. with food, with
what is perceptible, or with what is intelligible.
It follows that first of all we must treat of nutrition and reproduction, for the nutritive soul
is found along with all the others and is the most primitive and widely distributed power of soul,
being indeed that one in virtue of which all are said to have life. The acts in which it manifests
itself are reproduction and the use of food-reproduction, I say, because for any living thing that
has reached its normal development and which is unmutilated, and whose mode of generation is not
spontaneous, the most natural act is the production of another like itself, an animal producing an
animal, a plant a plant, in order that, as far as its nature allows, it may partake in the eternal
and divine. That is the goal towards which all things strive, that for the sake of which they do
whatsoever their nature renders possible. The phrase 'for the sake of which' is ambiguous; it may
mean either (a) the end to achieve which, or (b) the being in whose interest, the act is done. Since
then no living thing is able to partake in what is eternal and divine by uninterrupted continuance
(for nothing perishable can for ever remain one and the same), it tries to achieve that end in the
only way possible to it, and success is possible in varying degrees; so it remains not indeed as the
self-same individual but continues its existence in something like itself-not numerically but
specifically one.
The soul is the cause or source of the living body. The terms cause and source have many senses.
But the soul is the cause of its body alike in all three senses which we explicitly recognize. It is
(a) the source or origin of movement, it is (b) the end, it is (c) the essence of the whole living
body.
That it is the last, is clear; for in everything the essence is identical with the ground of its
being, and here, in the case of living things, their being is to live, and of their being and their
living the soul in them is the cause or source. Further, the actuality of whatever is potential is
identical with its formulable essence.
It is manifest that the soul is also the final cause of its body. For Nature, like mind, always
does whatever it does for the sake of something, which something is its end. To that something
corresponds in the case of animals the soul and in this it follows the order of nature; all natural
bodies are organs of the soul. This is true of those that enter into the constitution of plants as
well as of those which enter into that of animals. This shows that that the sake of which they are
is soul. We must here recall the two senses of 'that for the sake of which', viz. (a) the end to
achieve which, and (b) the being in whose interest, anything is or is done.
We must maintain, further, that the soul is also the cause of the living body as the original
source of local movement. The power of locomotion is not found, however, in all living things. But
change of quality and change of quantity are also due to the soul. Sensation is held to be a
qualitative alteration, and nothing except what has soul in it is capable of sensation. The same
holds of the quantitative changes which constitute growth and decay; nothing grows or decays
naturally except what feeds itself, and nothing feeds itself except what has a share of soul in it.
Empedocles is wrong in adding that growth in plants is to be explained, the downward rooting by
the natural tendency of earth to travel downwards, and the upward branching by the similar natural
tendency of fire to travel upwards. For he misinterprets up and down; up and down are not for all
things what they are for the whole Cosmos: if we are to distinguish and identify organs according to
their functions, the roots of plants are analogous to the head in animals. Further, we must ask what
is the force that holds together the earth and the fire which tend to travel in contrary directions;
if there is no counteracting force, they will be torn asunder; if there is, this must be the soul
and the cause of nutrition and growth. By some the element of fire is held to be the cause of
nutrition and growth, for it alone of the primary bodies or elements is observed to feed and
increase itself. Hence the suggestion that in both plants and animals it is it which is the
operative force. A concurrent cause in a sense it certainly is, but not the principal cause, that is
rather the soul; for while the growth of fire goes on without limit so long as there is a supply of
fuel, in the case of all complex wholes formed in the course of nature there is a limit or ratio
which determines their size and increase, and limit and ratio are marks of soul but not of fire, and
belong to the side of formulable essence rather than that of matter.
Nutrition and reproduction are due to one and the same psychic power. It is necessary first to
give precision to our account of food, for it is by this function of absorbing food that this
psychic power is distinguished from all the others. The current view is that what serves as food to
a living thing is what is contrary to it-not that in every pair of contraries each is food to the
other: to be food a contrary must not only be transformable into the other and vice versa, it must
also in so doing increase the bulk of the other. Many a contrary is transformed into its other and
vice versa, where neither is even a quantum and so cannot increase in bulk, e.g. an invalid into a
healthy subject. It is clear that not even those contraries which satisfy both the conditions
mentioned above are food to one another in precisely the same sense; water may be said to feed fire,
but not fire water. Where the members of the pair are elementary bodies only one of the contraries,
it would appear, can be said to feed the other. But there is a difficulty here. One set of thinkers
assert that like fed, as well as increased in amount, by like. Another set, as we have said,
maintain the very reverse, viz. that what feeds and what is fed are contrary to one another; like,
they argue, is incapable of being affected by like; but food is changed in the process of digestion,
and change is always to what is opposite or to what is intermediate. Further, food is acted upon by
what is nourished by it, not the other way round, as timber is worked by a carpenter and not
conversely; there is a change in the carpenter but it is merely a change from not-working to
working. In answering this problem it makes all the difference whether we mean by 'the food' the
'finished' or the 'raw' product. If we use the word food of both, viz. of the completely undigested
and the completely digested matter, we can justify both the rival accounts of it; taking food in the
sense of undigested matter, it is the contrary of what is fed by it, taking it as digested it is
like what is fed by it. Consequently it is clear that in a certain sense we may say that both
parties are right, both wrong.
Since nothing except what is alive can be fed, what is fed is the besouled body and just because
it has soul in it. Hence food is essentially related to what has soul in it. Food has a power which
is other than the power to increase the bulk of what is fed by it; so far forth as what has soul in
it is a quantum, food may increase its quantity, but it is only so far as what has soul in it is a
'this-somewhat' or substance that food acts as food; in that case it maintains the being of what is
fed, and that continues to be what it is so long as the process of nutrition continues. Further, it
is the agent in generation, i.e. not the generation of the individual fed but the reproduction of
another like it; the substance of the individual fed is already in existence; the existence of no
substance is a self-generation but only a self-maintenance.
Hence the psychic power which we are now studying may be described as that which tends to
maintain whatever has this power in it of continuing such as it was, and food helps it to do its
work. That is why, if deprived of food, it must cease to be.
The process of nutrition involves three factors, (a) what is fed, (b) that wherewith it is fed,
(c) what does the feeding; of these (c) is the first soul, (a) the body which has that soul in it,
(b) the food. But since it is right to call things after the ends they realize, and the end of this
soul is to generate another being like that in which it is, the first soul ought to be named the
reproductive soul. The expression (b) 'wherewith it is fed' is ambiguous just as is the expression
'wherewith the ship is steered'; that may mean either (i) the hand or (ii) the rudder, i.e. either
(i) what is moved and sets in movement, or (ii) what is merely moved. We can apply this analogy here
if we recall that all food must be capable of being digested, and that what produces digestion is
warmth; that is why everything that has soul in it possesses warmth.
We have now given an outline account of the nature of food; further details must be given in the
appropriate place.
II.5. Having made these distinctions let us now speak of sensation in the widest sense. Sensation
depends, as we have said, on a process of movement or affection from without, for it is held to be
some sort of change of quality. Now some thinkers assert that like is affected only by like; in what
sense this is possible and in what sense impossible, we have explained in our general discussion of
acting and being acted upon.
Here arises a problem: why do we not perceive the senses themselves as well as the external
objects of sense, or why without the stimulation of external objects do they not produce sensation,
seeing that they contain in themselves fire, earth, and all the other elements, which are the direct
or indirect objects is so of sense? It is clear that what is sensitive is only potentially, not
actually. The power of sense is parallel to what is combustible, for that never ignites itself
spontaneously, but requires an agent which has the power of starting ignition; otherwise it could
have set itself on fire, and would not have needed actual fire to set it ablaze.
In reply we must recall that we use the word 'perceive' in two ways, for we say (a) that what has
the power to hear or see, 'sees' or 'hears', even though it is at the moment asleep, and also (b)
that what is actually seeing or hearing, 'sees' or 'hears'. Hence 'sense' too must have two
meanings, sense potential, and sense actual. Similarly 'to be a sentient' means either (a) to have a
certain power or (b) to manifest a certain activity. To begin with, for a time, let us speak as if
there were no difference between (i) being moved or affected, and (ii) being active, for movement is
a kind of activity-an imperfect kind, as has elsewhere been explained. Everything that is acted upon
or moved is acted upon by an agent which is actually at work. Hence it is that in one sense, as has
already been stated, what acts and what is acted upon are like, in another unlike, i.e. prior to and
during the change the two factors are unlike, after it like.
But we must now distinguish not only between what is potential and what is actual but also
different senses in which things can be said to be potential or actual; up to now we have been
speaking as if each of these phrases had only one sense. We can speak of something as 'a knower'
either (a) as when we say that man is a knower, meaning that man falls within the class of beings
that know or have knowledge, or (b) as when we are speaking of a man who possesses a knowledge of
grammar; each of these is so called as having in him a certain potentiality, but there is a
difference between their respective potentialities, the one (a) being a potential knower, because
his kind or matter is such and such, the other (b), because he can in the absence of any external
counteracting cause realize his knowledge in actual knowing at will. This implies a third meaning of
'a knower' (c), one who is already realizing his knowledge-he is a knower in actuality and in the
most proper sense is knowing, e.g. this A. Both the former are potential knowers, who realize their
respective potentialities, the one (a) by change of quality, i.e. repeated transitions from one
state to its opposite under instruction, the other (b) by the transition from the inactive
possession of sense or grammar to their active exercise. The two kinds of transition are distinct.
Also the expression 'to be acted upon' has more than one meaning; it may mean either (a) the
extinction of one of two contraries by the other, or (b) the maintenance of what is potential by the
agency of what is actual and already like what is acted upon, with such likeness as is compatible
with one's being actual and the other potential. For what possesses knowledge becomes an actual
knower by a transition which is either not an alteration of it at all (being in reality a
development into its true self or actuality) or at least an alteration in a quite different sense
from the usual meaning.
Hence it is wrong to speak of a wise man as being 'altered' when he uses his wisdom, just as it
would be absurd to speak of a builder as being altered when he is using his skill in building a
house.
What in the case of knowing or understanding leads from potentiality to actuality ought not to be
called teaching but something else. That which starting with the power to know learns or acquires
knowledge through the agency of one who actually knows and has the power of teaching either (a)
ought not to be said 'to be acted upon' at all or (b) we must recognize two senses of alteration,
viz. (i) the substitution of one quality for another, the first being the contrary of the second, or
(ii) the development of an existent quality from potentiality in the direction of fixity or nature.
In the case of what is to possess sense, the first transition is due to the action of the male
parent and takes place before birth so that at birth the living thing is, in respect of sensation,
at the stage which corresponds to the possession of knowledge. Actual sensation corresponds to the
stage of the exercise of knowledge. But between the two cases compared there is a difference; the
objects that excite the sensory powers to activity, the seen, the heard, etc., are outside. The
ground of this difference is that what actual sensation apprehends is individuals, while what
knowledge apprehends is universals, and these are in a sense within the soul. That is why a man can
exercise his knowledge when he wishes, but his sensation does not depend upon himself a sensible
object must be there. A similar statement must be made about our knowledge of what is sensible-on
the same ground, viz. that the sensible objects are individual and external.
A later more appropriate occasion may be found thoroughly to clear up all this. At present it
must be enough to recognize the distinctions already drawn; a thing may be said to be potential in
either of two senses, (a) in the sense in which we might say of a boy that he may become a general
or (b) in the sense in which we might say the same of an adult, and there are two corresponding
senses of the term 'a potential sentient'. There are no separate names for the two stages of
potentiality; we have pointed out that they are different and how they are different. We cannot help
using the incorrect terms 'being acted upon or altered' of the two transitions involved. As we have
said, has the power of sensation is potentially like what the perceived object is actually; that is,
while at the beginning of the process of its being acted upon the two interacting factors are
dissimilar, at the end the one acted upon is assimilated to the other and is identical in quality
with it.
II.6. In dealing with each of the senses we shall have first to speak of the objects which are
perceptible by each. The term 'object of sense' covers three kinds of objects, two kinds of which
are, in our language, directly perceptible, while the remaining one is only incidentally
perceptible. Of the first two kinds one (a) consists of what is perceptible by a single sense, the
other (b) of what is perceptible by any and all of the senses. I call by the name of special object
of this or that sense that which cannot be perceived by any other sense than that one and in respect
of which no error is possible; in this sense colour is the special object of sight, sound of
hearing, flavour of taste. Touch, indeed, discriminates more than one set of different qualities.
Each sense has one kind of object which it discerns, and never errs in reporting that what is before
it is colour or sound (though it may err as to what it is that is coloured or where that is, or what
it is that is sounding or where that is.) Such objects are what we propose to call the special
objects of this or that sense.
'Common sensibles' are movement, rest, number, figure, magnitude; these are not peculiar to any
one sense, but are common to all. There are at any rate certain kinds of movement which are
perceptible both by touch and by sight.
We speak of an incidental object of sense where e.g. the white object which we see is the son of
Diares; here because 'being the son of Diares' is incidental to the directly visible white patch we
speak of the son of Diares as being (incidentally) perceived or seen by us. Because this is only
incidentally an object of sense, it in no way as such affects the senses. Of the two former kinds,
both of which are in their own nature perceptible by sense, the first kind-that of special objects
of the several senses-constitute the objects of sense in the strictest sense of the term and it is
to them that in the nature of things the structure of each several sense is adapted.
II.7. The object of sight is the visible, and what is visible is (a) colour and (b) a certain
kind of object which can be described in words but which has no single name; what we mean by (b)
will be abundantly clear as we proceed. Whatever is visible is colour and colour is what lies upon
what is in its own nature visible; 'in its own nature' here means not that visibility is involved in
the definition of what thus underlies colour, but that that substratum contains in itself the cause
of visibility. Every colour has in it the power to set in movement what is actually transparent;
that power constitutes its very nature. That is why it is not visible except with the help of light;
it is only in light that the colour of a thing is seen. Hence our first task is to explain what
light is.
Now there clearly is something which is transparent, and by 'transparent' I mean what is visible,
and yet not visible in itself, but rather owing its visibility to the colour of something else; of
this character are air, water, and many solid bodies. Neither air nor water is transparent because
it is air or water; they are transparent because each of them has contained in it a certain
substance which is the same in both and is also found in the eternal body which constitutes the
uppermost shell of the physical Cosmos. Of this substance light is the activity-the activity of what
is transparent so far forth as it has in it the determinate power of becoming transparent; where
this power is present, there is also the potentiality of the contrary, viz. darkness. Light is as it
were the proper colour of what is transparent, and exists whenever the potentially transparent is
excited to actuality by the influence of fire or something resembling 'the uppermost body'; for fire
too contains something which is one and the same with the substance in question.
We have now explained what the transparent is and what light is; light is neither fire nor any
kind whatsoever of body nor an efflux from any kind of body (if it were, it would again itself be a
kind of body)-it is the presence of fire or something resembling fire in what is transparent. It is
certainly not a body, for two bodies cannot be present in the same place. The opposite of light is
darkness; darkness is the absence from what is transparent of the corresponding positive state above
characterized; clearly therefore, light is just the presence of that.
Empedocles (and with him all others who used the same forms of expression) was wrong in speaking
of light as 'travelling' or being at a given moment between the earth and its envelope, its movement
being unobservable by us; that view is contrary both to the clear evidence of argument and to the
observed facts; if the distance traversed were short, the movement might have been unobservable, but
where the distance is from extreme East to extreme West, the draught upon our powers of belief is
too great.
What is capable of taking on colour is what in itself is colourless, as what can take on sound is
what is soundless; what is colourless includes (a) what is transparent and (b) what is invisible or
scarcely visible, i.e. what is 'dark'. The latter (b) is the same as what is transparent, when it is
potentially, not of course when it is actually transparent; it is the same substance which is now
darkness, now light.
Not everything that is visible depends upon light for its visibility. This is only true of the
'proper' colour of things. Some objects of sight which in light are invisible, in darkness stimulate
the sense; that is, things that appear fiery or shining. This class of objects has no simple common
name, but instances of it are fungi, flesh, heads, scales, and eyes of fish. In none of these is
what is seen their own proper' colour. Why we see these at all is another question. At present what
is obvious is that what is seen in light is always colour. That is why without the help of light
colour remains invisible. Its being colour at all means precisely its having in it the power to set
in movement what is already actually transparent, and, as we have seen, the actuality of what is
transparent is just light.
The following experiment makes the necessity of a medium clear. If what has colour is placed in
immediate contact with the eye, it cannot be seen. Colour sets in movement not the sense organ but
what is transparent, e.g. the air, and that, extending continuously from the object to the organ,
sets the latter in movement. Democritus misrepresents the facts when he expresses the opinion that
if the interspace were empty one could distinctly see an ant on the vault of the sky; that is an
impossibility. Seeing is due to an affection or change of what has the perceptive faculty, and it
cannot be affected by the seen colour itself; it remains that it must be affected by what comes
between. Hence it is indispensable that there be something in between-if there were nothing, so far
from seeing with greater distinctness, we should see nothing at all.
We have now explained the cause why colour cannot be seen otherwise than in light. Fire on the
other hand is seen both in darkness and in light; this double possibility follows necessarily from
our theory, for it is just fire that makes what is potentially transparent actually transparent.
The same account holds also of sound and smell; if the object of either of these senses is in
immediate contact with the organ no sensation is produced. In both cases the object sets in movement
only what lies between, and this in turn sets the organ in movement: if what sounds or smells is
brought into immediate contact with the organ, no sensation will be produced. The same, in spite of
all appearances, applies also to touch and taste; why there is this apparent difference will be
clear later. What comes between in the case of sounds is air; the corresponding medium in the case
of smell has no name. But, corresponding to what is transparent in the case of colour, there is a
quality found both in air and water, which serves as a medium for what has smell-I say 'in water'
because animals that live in water as well as those that live on land seem to possess the sense of
smell, and 'in air' because man and all other land animals that breathe, perceive smells only when
they breathe air in. The explanation of this too will be given later.
II.8. Now let us, to begin with, make certain distinctions about sound and hearing.
Sound may mean either of two things (a) actual, and (b) potential, sound. There are certain
things which, as we say, 'have no sound', e.g. sponges or wool, others which have, e.g. bronze and
in general all things which are smooth and solid-the latter are said to have a sound because they
can make a sound, i.e. can generate actual sound between themselves and the organ of hearing.
Actual sound requires for its occurrence (i, ii) two such bodies and (iii) a space between them;
for it is generated by an impact. Hence it is impossible for one body only to generate a sound-there
must be a body impinging and a body impinged upon; what sounds does so by striking against something
else, and this is impossible without a movement from place to place.
As we have said, not all bodies can by impact on one another produce sound; impact on wool makes
no sound, while the impact on bronze or any body which is smooth and hollow does. Bronze gives out a
sound when struck because it is smooth; bodies which are hollow owing to reflection repeat the
original impact over and over again, the body originally set in movement being unable to escape from
the concavity.
Further, we must remark that sound is heard both in air and in water, though less distinctly in
the latter. Yet neither air nor water is the principal cause of sound. What is required for the
production of sound is an impact of two solids against one another and against the air. The latter
condition is satisfied when the air impinged upon does not retreat before the blow, i.e. is not
dissipated by it.
That is why it must be struck with a sudden sharp blow, if it is to sound-the movement of the
whip must outrun the dispersion of the air, just as one might get in a stroke at a heap or whirl of
sand as it was traveling rapidly past.
An echo occurs, when, a mass of air having been unified, bounded, and prevented from dissipation
by the containing walls of a vessel, the air originally struck by the impinging body and set in
movement by it rebounds from this mass of air like a ball from a wall. It is probable that in all
generation of sound echo takes place, though it is frequently only indistinctly heard. What happens
here must be analogous to what happens in the case of light; light is always reflected-otherwise it
would not be diffused and outside what was directly illuminated by the sun there would be blank
darkness; but this reflected light is not always strong enough, as it is when it is reflected from
water, bronze, and other smooth bodies, to cast a shadow, which is the distinguishing mark by which
we recognize light.
It is rightly said that an empty space plays the chief part in the production of hearing, for
what people mean by 'the vacuum' is the air, which is what causes hearing, when that air is set in
movement as one continuous mass; but owing to its friability it emits no sound, being dissipated by
impinging upon any surface which is not smooth. When the surface on which it impinges is quite
smooth, what is produced by the original impact is a united mass, a result due to the smoothness of
the surface with which the air is in contact at the other end.
What has the power of producing sound is what has the power of setting in movement a single mass
of air which is continuous from the impinging body up to the organ of hearing. The organ of hearing
is physically united with air, and because it is in air, the air inside is moved concurrently with
the air outside. Hence animals do not hear with all parts of their bodies, nor do all parts admit of
the entrance of air; for even the part which can be moved and can sound has not air everywhere in
it. Air in itself is, owing to its friability, quite soundless; only when its dissipation is
prevented is its movement sound. The air in the ear is built into a chamber just to prevent this
dissipating movement, in order that the animal may accurately apprehend all varieties of the
movements of the air outside. That is why we hear also in water, viz. because the water cannot get
into the air chamber or even, owing to the spirals, into the outer ear. If this does happen, hearing
ceases, as it also does if the tympanic membrane is damaged, just as sight ceases if the membrane
covering the pupil is damaged. It is also a test of deafness whether the ear does or does not
reverberate like a horn; the air inside the ear has always a movement of its own, but the sound we
hear is always the sounding of something else, not of the organ itself. That is why we say that we
hear with what is empty and echoes, viz. because what we hear with is a chamber which contains a
bounded mass of air.
Which is it that 'sounds', the striking body or the struck? Is not the answer 'it is both, but
each in a different way'? Sound is a movement of what can rebound from a smooth surface when struck
against it. As we have explained' not everything sounds when it strikes or is struck, e.g. if one
needle is struck against another, neither emits any sound. In order, therefore, that sound may be
generated, what is struck must be smooth, to enable the air to rebound and be shaken off from it in
one piece.
The distinctions between different sounding bodies show themselves only in actual sound; as
without the help of light colours remain invisible, so without the help of actual sound the
distinctions between acute and grave sounds remain inaudible. Acute and grave are here metaphors,
transferred from their proper sphere, viz. that of touch, where they mean respectively (a) what
moves the sense much in a short time, (b) what moves the sense little in a long time. Not that what
is sharp really moves fast, and what is grave, slowly, but that the difference in the qualities of
the one and the other movement is due to their respective speeds. There seems to be a sort of
parallelism between what is acute or grave to hearing and what is sharp or blunt to touch; what is
sharp as it were stabs, while what is blunt pushes, the one producing its effect in a short, the
other in a long time, so that the one is quick, the other slow.
Let the foregoing suffice as an analysis of sound. Voice is a kind of sound characteristic of
what has soul in it; nothing that is without soul utters voice, it being only by a metaphor that we
speak of the voice of the flute or the lyre or generally of what (being without soul) possesses the
power of producing a succession of notes which differ in length and pitch and timbre. The metaphor
is based on the fact that all these differences are found also in voice. Many animals are voiceless,
e.g. all non-sanuineous animals and among sanguineous animals fish. This is just what we should
expect, since voice is a certain movement of air. The fish, like those in the Achelous, which are
said to have voice, really make the sounds with their gills or some similar organ. Voice is the
sound made by an animal, and that with a special organ. As we saw, everything that makes a sound
does so by the impact of something (a) against something else, (b) across a space, (c) filled with
air; hence it is only to be expected that no animals utter voice except those which take in air.
Once air is inbreathed, Nature uses it for two different purposes, as the tongue is used both for
tasting and for articulating; in that case of the two functions tasting is necessary for the
animal's existence (hence it is found more widely distributed), while articulate speech is a luxury
subserving its possessor's well-being; similarly in the former case Nature employs the breath both
as an indispensable means to the regulation of the inner temperature of the living body and also as
the matter of articulate voice, in the interests of its possessor's well-being. Why its former use
is indispensable must be discussed elsewhere.
The organ of respiration is the windpipe, and the organ to which this is related as means to end
is the lungs. The latter is the part of the body by which the temperature of land animals is raised
above that of all others. But what primarily requires the air drawn in by respiration is not only
this but the region surrounding the heart. That is why when animals breathe the air must penetrate
inwards.
Voice then is the impact of the inbreathed air against the 'windpipe', and the agent that
produces the impact is the soul resident in these parts of the body. Not every sound, as we said,
made by an animal is voice (even with the tongue we may merely make a sound which is not voice, or
without the tongue as in coughing); what produces the impact must have soul in it and must be
accompanied by an act of imagination, for voice is a sound with a meaning, and is not merely the
result of any impact of the breath as in coughing; in voice the breath in the windpipe is used as an
instrument to knock with against the walls of the windpipe. This is confirmed by our inability to
speak when we are breathing either out or in-we can only do so by holding our breath; we make the
movements with the breath so checked. It is clear also why fish are voiceless; they have no
windpipe. And they have no windpipe because they do not breathe or take in air. Why they do not is a
question belonging to another inquiry.
II.9. Smell and its object are much less easy to determine than what we have hitherto discussed;
the distinguishing characteristic of the object of smell is less obvious than those of sound or
colour. The ground of this is that our power of smell is less discriminating and in general inferior
to that of many species of animals; men have a poor sense of smell and our apprehension of its
proper objects is inseparably bound up with and so confused by pleasure and pain, which shows that
in us the organ is inaccurate. It is probable that there is a parallel failure in the perception of
colour by animals that have hard eyes: probably they discriminate differences of colour only by the
presence or absence of what excites fear, and that it is thus that human beings distinguish smells.
It seems that there is an analogy between smell and taste, and that the species of tastes run
parallel to those of smells-the only difference being that our sense of taste is more discriminating
than our sense of smell, because the former is a modification of touch, which reaches in man the
maximum of discriminative accuracy. While in respect of all the other senses we fall below many
species of animals, in respect of touch we far excel all other species in exactness of
discrimination. That is why man is the most intelligent of all animals. This is confirmed by the
fact that it is to differences in the organ of touch and to nothing else that the differences
between man and man in respect of natural endowment are due; men whose flesh is hard are ill-endowed
by nature, men whose flesh is soft, wellendowed.
As flavours may be divided into (a) sweet, (b) bitter, so with smells. In some things the flavour
and the smell have the same quality, i.e. both are sweet or both bitter, in others they diverge.
Similarly a smell, like a flavour, may be pungent, astringent, acid, or succulent. But, as we said,
because smells are much less easy to discriminate than flavours, the names of these varieties are
applied to smells only metaphorically; for example 'sweet' is extended from the taste to the smell
of saffron or honey, 'pungent' to that of thyme, and so on.
In the same sense in which hearing has for its object both the audible and the inaudible, sight
both the visible and the invisible, smell has for its object both the odorous and the inodorous.
'Inodorous' may be either (a) what has no smell at all, or (b) what has a small or feeble smell. The
same ambiguity lurks in the word 'tasteless'.
Smelling, like the operation of the senses previously examined, takes place through a medium,
i.e. through air or water-I add water, because water-animals too (both sanguineous and
non-sanguineous) seem to smell just as much as land-animals; at any rate some of them make directly
for their food from a distance if it has any scent. That is why the following facts constitute a
problem for us. All animals smell in the same way, but man smells only when he inhales; if he
exhales or holds his breath, he ceases to smell, no difference being made whether the odorous object
is distant or near, or even placed inside the nose and actually on the wall of the nostril; it is a
disability common to all the senses not to perceive what is in immediate contact with the organ of
sense, but our failure to apprehend what is odorous without the help of inhalation is peculiar (the
fact is obvious on making the experiment). Now since bloodless animals do not breathe, they must, it
might be argued, have some novel sense not reckoned among the usual five. Our reply must be that
this is impossible, since it is scent that is perceived; a sense that apprehends what is odorous and
what has a good or bad odour cannot be anything but smell. Further, they are observed to be
deleteriously effected by the same strong odours as man is, e.g. bitumen, sulphur, and the like.
These animals must be able to smell without being able to breathe. The probable explanation is that
in man the organ of smell has a certain superiority over that in all other animals just as his eyes
have over those of hard-eyed animals. Man's eyes have in the eyelids a kind of shelter or envelope,
which must be shifted or drawn back in order that we may see, while hardeyed animals have nothing of
the kind, but at once see whatever presents itself in the transparent medium. Similarly in certain
species of animals the organ of smell is like the eye of hard-eyed animals, uncurtained, while in
others which take in air it probably has a curtain over it, which is drawn back in inhalation, owing
to the dilating of the veins or pores. That explains also why such animals cannot smell under water;
to smell they must first inhale, and that they cannot do under water.
Smells come from what is dry as flavours from what is moist. Consequently the organ of smell is
potentially dry.
II.10. What can be tasted is always something that can be touched, and just for that reason it
cannot be perceived through an interposed foreign body, for touch means the absence of any
intervening body. Further, the flavoured and tasteable body is suspended in a liquid matter, and
this is tangible. Hence, if we lived in water, we should perceive a sweet object introduced into the
water, but the water would not be the medium through which we perceived; our perception would be due
to the solution of the sweet substance in what we imbibed, just as if it were mixed with some drink.
There is no parallel here to the perception of colour, which is due neither to any blending of
anything with anything, nor to any efflux of anything from anything. In the case of taste, there is
nothing corresponding to the medium in the case of the senses previously discussed; but as the
object of sight is colour, so the object of taste is flavour. But nothing excites a perception of
flavour without the help of liquid; what acts upon the sense of taste must be either actually or
potentially liquid like what is saline; it must be both (a) itself easily dissolved, and (b) capable
of dissolving along with itself the tongue. Taste apprehends both (a) what has taste and (b) what
has no taste, if we mean by (b) what has only a slight or feeble flavour or what tends to destroy
the sense of taste. In this it is exactly parallel to sight, which apprehends both what is visible
and what is invisible (for darkness is invisible and yet is discriminated by sight; so is, in a
different way, what is over brilliant), and to hearing, which apprehends both sound and silence, of
which the one is audible and the other inaudible, and also over-loud sound. This corresponds in the
case of hearing to over-bright light in the case of sight. As a faint sound is 'inaudible', so in a
sense is a loud or violent sound. The word 'invisible' and similar privative terms cover not only
(a) what is simply without some power, but also (b) what is adapted by nature to have it but has not
it or has it only in a very low degree, as when we say that a species of swallow is 'footless' or
that a variety of fruit is 'stoneless'. So too taste has as its object both what can be tasted and
the tasteless-the latter in the sense of what has little flavour or a bad flavour or one destructive
of taste. The difference between what is tasteless and what is not seems to rest ultimately on that
between what is drinkable and what is undrinkable both are tasteable, but the latter is bad and
tends to destroy taste, while the former is the normal stimulus of taste. What is drinkable is the
common object of both touch and taste.
Since what can be tasted is liquid, the organ for its perception cannot be either (a) actually
liquid or (b) incapable of becoming liquid. Tasting means a being affected by what can be tasted as
such; hence the organ of taste must be liquefied, and so to start with must be non-liquid but
capable of liquefaction without loss of its distinctive nature. This is confirmed by the fact that
the tongue cannot taste either when it is too dry or when it is too moist; in the latter case what
occurs is due to a contact with the pre-existent moisture in the tongue itself, when after a
foretaste of some strong flavour we try to taste another flavour; it is in this way that sick
persons find everything they taste bitter, viz. because, when they taste, their tongues are
overflowing with bitter moisture.
The species of flavour are, as in the case of colour, (a) simple, i.e. the two contraries, the
sweet and the bitter, (b) secondary, viz. (i) on the side of the sweet, the succulent, (ii) on the
side of the bitter, the saline, (iii) between these come the pungent, the harsh, the astringent, and
the acid; these pretty well exhaust the varieties of flavour. It follows that what has the power of
tasting is what is potentially of that kind, and that what is tasteable is what has the power of
making it actually what it itself already is.
II.11. Whatever can be said of what is tangible, can be said of touch, and vice versa; if touch
is not a single sense but a group of senses, there must be several kinds of what is tangible. It is
a problem whether touch is a single sense or a group of senses. It is also a problem, what is the
organ of touch; is it or is it not the flesh (including what in certain animals is homologous with
flesh)? On the second view, flesh is 'the medium' of touch, the real organ being situated farther
inward. The problem arises because the field of each sense is according to the accepted view
determined as the range between a single pair of contraries, white and black for sight, acute and
grave for hearing, bitter and sweet for taste; but in the field of what is tangible we find several
such pairs, hot cold, dry moist, hard soft, etc. This problem finds a partial solution, when it is
recalled that in the case of the other senses more than one pair of contraries are to be met with,
e.g. in sound not only acute and grave but loud and soft, smooth and rough, etc.; there are similar
contrasts in the field of colour. Nevertheless we are unable clearly to detect in the case of touch
what the single subject is which underlies the contrasted qualities and corresponds to sound in the
case of hearing.
To the question whether the organ of touch lies inward or not (i.e. whether we need look any
farther than the flesh), no indication in favour of the second answer can be drawn from the fact
that if the object comes into contact with the flesh it is at once perceived. For even under present
conditions if the experiment is made of making a web and stretching it tight over the flesh, as soon
as this web is touched the sensation is reported in the same manner as before, yet it is clear that
the or is gan is not in this membrane. If the membrane could be grown on to the flesh, the report
would travel still quicker. The flesh plays in touch very much the same part as would be played in
the other senses by an air-envelope growing round our body; had we such an envelope attached to us
we should have supposed that it was by a single organ that we perceived sounds, colours, and smells,
and we should have taken sight, hearing, and smell to be a single sense. But as it is, because that
through which the different movements are transmitted is not naturally attached to our bodies, the
difference of the various sense-organs is too plain to miss. But in the case of touch the obscurity
remains.
There must be such a naturally attached 'medium' as flesh, for no living body could be
constructed of air or water; it must be something solid. Consequently it must be composed of earth
along with these, which is just what flesh and its analogue in animals which have no true flesh tend
to be. Hence of necessity the medium through which are transmitted the manifoldly contrasted tactual
qualities must be a body naturally attached to the organism. That they are manifold is clear when we
consider touching with the tongue; we apprehend at the tongue all tangible qualities as well as
flavour. Suppose all the rest of our flesh was, like the tongue, sensitive to flavour, we should
have identified the sense of taste and the sense of touch; what saves us from this identification is
the fact that touch and taste are not always found together in the same part of the body. The
following problem might be raised. Let us assume that every body has depth, i.e. has three
dimensions, and that if two bodies have a third body between them they cannot be in contact with one
another; let us remember that what is liquid is a body and must be or contain water, and that if two
bodies touch one another under water, their touching surfaces cannot be dry, but must have water
between, viz. the water which wets their bounding surfaces; from all this it follows that in water
two bodies cannot be in contact with one another. The same holds of two bodies in air-air being to
bodies in air precisely what water is to bodies in water-but the facts are not so evident to our
observation, because we live in air, just as animals that live in water would not notice that the
things which touch one another in water have wet surfaces. The problem, then, is: does the
perception of all objects of sense take place in the same way, or does it not, e.g. taste and touch
requiring contact (as they are commonly thought to do), while all other senses perceive over a
distance? The distinction is unsound; we perceive what is hard or soft, as well as the objects of
hearing, sight, and smell, through a 'medium', only that the latter are perceived over a greater
distance than the former; that is why the facts escape our notice. For we do perceive everything
through a medium; but in these cases the fact escapes us. Yet, to repeat what we said before, if the
medium for touch were a membrane separating us from the object without our observing its existence,
we should be relatively to it in the same condition as we are now to air or water in which we are
immersed; in their case we fancy we can touch objects, nothing coming in between us and them. But
there remains this difference between what can be touched and what can be seen or can sound; in the
latter two cases we perceive because the medium produces a certain effect upon us, whereas in the
perception of objects of touch we are affected not by but along with the medium; it is as if a man
were struck through his shield, where the shock is not first given to the shield and passed on to
the man, but the concussion of both is simultaneous.
In general, flesh and the tongue are related to the real organs of touch and taste, as air and
water are to those of sight, hearing, and smell. Hence in neither the one case nor the other can
there be any perception of an object if it is placed immediately upon the organ, e.g. if a white
object is placed on the surface of the eye. This again shows that what has the power of perceiving
the tangible is seated inside. Only so would there be a complete analogy with all the other senses.
In their case if you place the object on the organ it is not perceived, here if you place it on the
flesh it is perceived; therefore flesh is not the organ but the medium of touch.
What can be touched are distinctive qualities of body as body; by such differences I mean those
which characterize the elements, viz, hot cold, dry moist, of which we have spoken earlier in our
treatise on the elements. The organ for the perception of these is that of touch-that part of the
body in which primarily the sense of touch resides. This is that part which is potentially such as
its object is actually: for all sense-perception is a process of being so affected; so that that
which makes something such as it itself actually is makes the other such because the other is
already potentially such. That is why when an object of touch is equally hot and cold or hard and
soft we cannot perceive; what we perceive must have a degree of the sensible quality lying beyond
the neutral point. This implies that the sense itself is a 'mean' between any two opposite qualities
which determine the field of that sense. It is to this that it owes its power of discerning the
objects in that field. What is 'in the middle' is fitted to discern; relatively to either extreme it
can put itself in the place of the other. As what is to perceive both white and black must, to begin
with, be actually neither but potentially either (and so with all the other sense-organs), so the
organ of touch must be neither hot nor cold.
Further, as in a sense sight had for its object both what was visible and what was invisible (and
there was a parallel truth about all the other senses discussed), so touch has for its object both
what is tangible and what is intangible. Here by 'intangible' is meant (a) what like air possesses
some quality of tangible things in a very slight degree and (b) what possesses it in an excessive
degree, as destructive things do.
We have now given an outline account of each of the several senses.
II.12. The following results applying to any and every sense may now be formulated.
(A) By a 'sense' is meant what has the power of receiving into itself the sensible forms of
things without the matter. This must be conceived of as taking place in the way in which a piece of
wax takes on the impress of a signet-ring without the iron or gold; we say that what produces the
impression is a signet of bronze or gold, but its particular metallic constitution makes no
difference: in a similar way the sense is affected by what is coloured or flavoured or sounding, but
it is indifferent what in each case the substance is; what alone matters is what quality it has,
i.e. in what ratio its constituents are combined.
(B) By 'an organ of sense' is meant that in which ultimately such a power is seated.
The sense and its organ are the same in fact, but their essence is not the same. What perceives
is, of course, a spatial magnitude, but we must not admit that either the having the power to
perceive or the sense itself is a magnitude; what they are is a certain ratio or power in a
magnitude. This enables us to explain why objects of sense which possess one of two opposite
sensible qualities in a degree largely in excess of the other opposite destroy the organs of sense;
if the movement set up by an object is too strong for the organ, the equipoise of contrary qualities
in the organ, which just is its sensory power, is disturbed; it is precisely as concord and tone are
destroyed by too violently twanging the strings of a lyre. This explains also why plants cannot
perceive. in spite of their having a portion of soul in them and obviously being affected by
tangible objects themselves; for undoubtedly their temperature can be lowered or raised. The
explanation is that they have no mean of contrary qualities, and so no principle in them capable of
taking on the forms of sensible objects without their matter; in the case of plants the affection is
an affection by form-and-matter together. The problem might be raised: Can what cannot smell be said
to be affected by smells or what cannot see by colours, and so on? It might be said that a smell is
just what can be smelt, and if it produces any effect it can only be so as to make something smell
it, and it might be argued that what cannot smell cannot be affected by smells and further that what
can smell can be affected by it only in so far as it has in |
Enigma of
Consciousness