Book 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.
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 t
hey 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.
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, c., 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