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December, 1874.


full one. A man of science, on the other hand, explains
as much as ever he can, and then he says, ' This is all
/ I can do ; for the rest you must ask the next man.'
And with regard to such explanations as he has given,
whether the next man comes at all, whether there is
any next man or any further explanation or no (and we
may have to wait hundreds or even thousands of years
before another step is made), yet if the original step
was a scientific step, was made by true scientific methods,
and was an organization of the normal experience of
healthy men, that step will remain good for ever, no
matter how much is left unexplained by it.

Now the supposition that this subject in itself is
necessarily one which cannot be discussed to good pur-
pose, that is to say, in such a way as to lead to definite
results, is a mistake. The fact that the subject has been
discussed for many hundreds of years to no good pur-
pose, and without leading to definite results, by great
numbers of people, is due to the method which was
employed, and not to the subject itself; and, in fact, if
we like to look in the same way upon other subjects as
we have been accustomed to look upon metaphysics
if we regard every man who has written about mathe-
matics or mechanics as having just the same right to
speak and to be heard that we give to every man who
has written about metaphysics then I think we shall
find that exactly the same thing can be said about the
most certain regions of human science.

Those who like to read the last number of the
'Edinburgh Eeview,' 1 for example, will find, from an
article on ' Comets and Meteors,' that it is at present quite

1 October, 1874.


an open question whether bodies which are shot out from
the sun by eruptive force may not come to circle about
the sun in orbits which are like those of the planets,
^ow that is not an open question ; the supposition is an
utterly absurd one, and has been utterly absurd from
The time of Kepler. Again, those who are curious
enough to read a number of pamphlets that are to be
found here and there may think it is an open question
whether the ratio of the circumference of a circle to its
diameter may not be expressed by certain finite numbers.
It is not an open question to Science ; it is only open to
those people who do not know any Trigonometry, and
who will not learn it. Ijn exactly the same way there
are numbers of questions relating to the connexion of
the mind with the body which have ceased to be open
questions, because Science has had her word to say
about them ; and they are only open now to people
who do not know what that word of Science is, and
who will not try to learn it.J

The whole field of human knowledge may be divided
roughly, for the sake of convenience, into three great
regions. There are first of all what we call par excel-
lence the Physical Sciences those which deal with in-
animate matter. Next, there are those sciences which
deal with organic bodies the bodies of living things,
whether plants or animals, and the rules according to
which those things move. And lastly, there are those
sciences which make a further supposition which sup-
pose that besides this physical world, including both
organic and inorganic bodies, there are also certain
other facts, namely, that other men besides me, and
most likely other animals besides men, are conscious.



The sciences which make that supposition are the
sciences of Ethics and Politics, which are still in the
practical stage, and especially the more advanced science
which is now to be considered Psychology, the Science
of Mind itself; that is to say, the science of the laws
which regulate the succession of feelings in any one
consciousness. Each of these three great divisions
began in the form of a number of perfectly disconnected
subjects, between which nobody knew of any relation ;
but in the history of science each of them has been
woven together, in consequence of connexions being
found between the different subjects included in it, into
a complete whole ; and the further progress of the
history of science requires that each of these great
threads, into which all the little threads have been
twined, should themselves be twined together into a
single string.

With regard to the first two groups, the group
of mechanical sciences as we may call them, or the
physics of inorganic bodies, and the group of biological
sciences, or the physics of organic bodies the gulf
between these two has in these last days been firmly
bridged over. A description of that bridge, and an
account of the doctrines which form it, will be found
in Professor Huxley's admirable lecture delivered at
Belfast before the British Association. That bridge,
as we have it now, is, in the conception of it, mainly
due to Descartes ; but parts of it have been worked
out since his time by a vast number of physiologists,
with the expenditure of an enormous amount of
labour and thought. Such facts as that discovered by
Harvey, that the movement of the blood was a mere


question of Tlydrodynanrics, and was to be explained
upon the same principles as the motion of water in pipes
facts like these have been piled up, one upon another,
and have gradually led to the conclusion that the
science of organic bodies is only a complication of the
science of inorganic bodies.

It would not be advisable here to describe in detail
the stones which compose this bridge ; but we have to
ask whether it is possible to construct some similar
bridge between the now united Science of Physics,
which deals with all phenomena, whether organic or
inorganic, in fact with all the material world, and the
other science, the Science of Consciousness, which deals
with the Laws of Mind and with the subject of Ethics.
This is the question which we have now to discuss.

In order to make this bridge a firm one, so that it
will not break down like those which philosophers have
made, it is necessary to observe with great care what is
the exact difference between the twojJasses of facts. If
we confuse the two things together to begin with, if we
do not recognize the great difference between them, we
shall not be likely to find any explanation which will
reduce them to some common term. C^he first thing,
therefore, that we have to do is to realize as clearly as
possible how profound the gulf is between the facts
which we call Physical facts and the facts which we
call Mental factsf] The difference is one which has been
observed from primeval times, when man or his pre-
human ancestor found it not good to be alone ; for the
very earliest precept that we firid set forth in all
societies to regulate the lives of those who belong to
them, is, ' Put yourself in his place ; ' that is to say,

D 2


ascribe to other men a consciousness "which is like your
own. And this belief, which the lowest savage got, that
there was something else than the physical organization
in other men, is the foundation of Natural Ethics as
well as of the modern Science of Consciousness. But
in very early times an hypothesis was formed which
was supposed to make this belief easier. If you eat too
much you will dream when you are asleep ; if you eat
too little you will dream when you are awake, or have
visions ; and those dreams of savages whose food was
very precarious led them to a biological hypothesis.
They saw in those dreams their fellows, other men,
when it appeared from evidence furnished to them
afterwards that those other men were not there when
they were dreaming. Consequently they supposed
that the actions of the organic body were caused by
some other body which was not physical in the ordinary
sense, which was not made of ordinary matter, and this
other body was called the Soul. Animism, as Mr.
Tylor calls this belief, was at first, then, an hypothesis
in the domain of biology. It was a physical hypothesis
to account for the peculiar way in which living things
went about. But then when people had got this belief
in another body which was not a physical body, after a
long series of years they reasoned in this way. It is
very difficult indeed, to suppose that the ordinary matter
which makes a man's body can be conscious. This Me
is quite different from the flesh and blood which make
up a man ; but then as to this other body, or soul, we
do not know anything about it, so that it may as well
be conscious as not. That hypothesis put upon the soul,
whose basis was in the phenomena of dreams, the


explanation of the consciousness which we cannot help
believing to exist in other men. I have mentioned this
early hypothesis on the subject, because out of it grew
the almost universal custom of holding at this time of
the year the Festival of the Dead which we preserve in
our All Souls' Day.

But now let us see what it is that Science can tell
us and what we can believe in place of that early
hypothesis of our savage ancestors. In the first place,
let us consider a little more narrowly what we mean by
the body, and more especially what we mean by the
nervous system ; for it is the great discovery of
Descartes that the nervous system is that part of the ;
body which is related directly to the mind. This can
hardly be better expressed than it is by the first of that
series of propositions which Professor Huxley has stated
in his lecture.

I. ' The brain is the organ of sensation, thought, and
emotion ; that is to say, some change in the condition of
the matter of this organ is the invariable antecedent of the
state of consciousness to which each of these terms is
applied' We may complete this statement by saying
not only that some change in the matter of this organ
is the invariable antecedent, but that some other change
is the invariable concomitant of sensation, thought, and
emotion ; and that is rather an important remark, as
you will see presently.

Let us now look at the general structure of the
brain and see what it is like. We can easily make a
rough picture of it, which will serve our present
purpose. 1 A parachute is a round piece of paper,

1 [See the diagram at p. 43 below.]


like the top of a parasol, with strings going from its
circumference to a cork. Let us imagine a parachute
with two corks, a red and a blue one; each .of these
corks being attached by strings, not only to the circuni
ference of our piece of paper, but to innumerable
points in the inside of it. Moreover, let innumerable
other strings go across from point to point of the paper,
like a spider's web spun in the inside of a parasol.
And the corks themselves must be tied to each other
and to a third cork, say a white one, while from all
three streamers fly away in all directions.

This is our diagram. Now the sheet of paper re-
presents the cerebral hemispheres, a great sheet of grey
nervous matter which forms the outside of your brain,
and lies just under your skull. Our red and blue corks
are two other masses of grey matter lying at the base of
the brain, and called the optic thalami and the corpora
striata respectively. The white cork is another mass of
grey matter called the medulla oblong ata, which is the
top of the spinal cord. Our strings which tie part of
the parachute together, and our streamers which go out
in all directions from the corks, represent the nerves,
white threads that run all over the body. And they are
of two kinds : there are some which go to the brain from
any part of the body, and others which come from the
brain to it. As regards the position of the nerves this
is the same thing for both of them, but it is not the
same thing with regard to what they do. The nerves
which are called Sensory nerves, and which go to the
brain, are those which are excited whenever any part of
the body is touched. When your finger is touched, a
certain excitement is given to the nerves which end in


>ur finger, and that excitement is carried along your
arm and away up to the medulla, represented by our
white cork. But when you are going to move your arm
the excitement starts from the brain, and goes along the
other set of nerves which are called Motor nerves, or
moving nerves, and goes to the muscles which work the
part of the arm which you want to move. And that
excitement of the nerves by purely mechanical means
makes those muscles contract so as to move the part
which you want to move. We have then a connexion
between the brain and any part of the body which is of
a double kind : there is the means of sending a message
to the brain from this part of the body, and the means
of taking a message from the brain to this part. The
nerves which carry the message to the brain are called
the ' Sensory nerves,' because they accompany what we
call sensation ; the nerves which carry the message from
the brain are called ' Motor nerves,' because they are
the agents in the motion of that part of the body.

All this is expressed in Professor Huxley's second
and third propositions.

n. ' The movements of animals are due to the change
of form of the muscles, which shorten and become thicker ;
and this change of form in a muscle arises from a motion
of the substance contained within the nerves which go to the

m. ' The sensations of animals are due to a motion of
the substance of the nerves which connect the sensory organs
with the brain J

I pass on to his fourth proposition :

IV. ' The motion of the matter of a sensory nerve may
be transmitted through the brain to motor nerves, and


thereby give rise to a contraction of the muscles to which
these motor nerves are distributed; and tf : 9 refaction of
motion from a sensory into a motor ne >iay take pl<i<'<'
without volition, or even contrary to it.'

Let us take that organ of sense which always occurs
to us as a type of the others, because it is the
perfect the eye. The optic nerve which runs from
eye towards the brain may be represented by on 3 ^ four
streamers going to the red cork, to which it is fastened
by a knot that is called the ' Optic ganglion/ Suppos-
ing that you move your hand rapidly towards anybody's
eye, a message with news of this movement goes along
the nerve to the optic ganglion, and it comes away back
again by another streamer, not direct from the ganglion,
but from a point on the blue cork very near it, to the
muscles which move the eyelid, and that makes the eye
wink. You know that the winking of the eye, when
anybody moves his hand very rapidly towards it, is not
a thing which you determine to do, and which you con-
sider about ; it is a thing which happens without your in-
terference with it ; and in fact it is not you who wink
your eye, but your body that does it. This is called
Automatic or involuntary motion, or again it is called
Reflex action, because it is a purely mechanical thing.
A wave runs along that nerve, and comes back on
another nerve, and that without any deliberation ; and
at the point where it stops and comes back it is just a
reflection like the wave which you send along a string,
and which comes back from the end of the string, or like
a wave of water which is sent up against a sea-wall, and
which reflects itself back along the sea.

V. ' The motion of any given portion of the matter of


the brain, tv >tiun of a sensory nerve, leaves

behind it a readiness to be moved in the same way in that
part. 't'hich resuscitates the motion gives rise

to the appropriate feeling. This is the physical mechanism

ternary' We can, perhaps, make this a little more
clear in the following manner : Suppose two messages
are se-nt at once to the brain ; each of them is reflected
back, but the two disturbances which they set up in the
brain create, in some way or other, a link between them,
so that when one of these disturbances is set up after-
wards the other one is also set up. It is as if every time
two bells of a house were rung together, that of itself
made a string to tie them together, so that when you
rang one bell it was necessary to ring the other bell in
consequence. That, remember, is purely a physical
circumstance of which we know that it happens. There
is a physical excitation or disturbance which is sent along
two different nerves, and which produces two different
disturbances in the brain, and the effect of these two
disturbances taking place together is to make a change
in the character of the brain itself, so that when the one
of them takes place it produces the other.

Now there are two different ways in which a stimulus
coming to the eye can be made to move the hand. In
the first place, suppose you are copying out a book;
you have the book before you, and you read the book
whilst you are copying with your hand, and conse-
quently the light coming into your eye from the book
directs your hand to move in a certain way. It is
possible for this light impinging upon the eye to send a
message along the optic nerve into the ganglion, and
that message may go almost, though not quite, direct


to the hand, so as to make the hand move, and that
causes the hand to describe the letter which you have
seen in the book ; or else the message may go by
longer route which takes more time. A simple experi-
ment to distinguish between these processes was tried"
by Bonders, the great Dutch physiologist. He made a
sign to a man at a distance, and when he made this sign
the man was to put down a key with his hand. He
measured the time which was taken in this process, that
is to say, the time which was taken by the message in
going from the eye to the ganglion, and then to the
hand. Measurements of the rate of nerve-motions have
also been made by Helmholtz. The velocity varies to
a certain extent in different people, but it is something
like one hundred feet a second. But Bonders also
made another measurement. Suppose it is not decided
beforehand whether the man is to move the key with
his right or left hand, and this is to be determined by
the nature of the signal, then before he can move his
hand he has to decide which hand he will use. The
time taken for that process of decision was also
measured. That process of decision, when looked at
from the physical side, means this. The message goes
up from the eye to the ganglion. It is immediately
connected there with the mass of grey matter repre-
sented by our red cork. From that mass of grey
matter there go white threads away to the whole of the
surface of the cerebral hemispheres, or the paper of
our parachute, and they take that message, therefore,
which comes from the eye to the ganglion away to all
this grey matter which is put round the inside of your
skull. There are also white threads which connect all


the parts of fcbis grey matter together, and they run
across from every pa^t of it to almost every other part
c* it. As soon as a message has been taken to this grey

ter, there is a vast interchange of messages going
on between those parts ; but finally, as the result of
that, a number of messages come upon other white
threads to another piece of grey matter, which is re-
presented by our blue cork ; from that the message is
then taken to the muscles of the hand. There are then
two different ways in which a message may go from the
eye to the hand. It may go to the optic ganglion, and
then almost straight to the hand, and in that case you
do not know much about it you only know that some-
thing has taken place, you do not think that you have
done it yourself ; or it may go to the optic ganglion,
and be sent up to the cerebral hemispheres, and then
be sent back to the sensory tract and then on to the
hand. But that takes more time, and it implies that
you have deliberated upon the act.

The diagram here drawn may make this point more
clear. Here E is the eye, K and B are the red and blue


orks, and H is the hand. The curve C C represents
the cerebral hemispheres, or the top of our parachute.


If the action is so habitually associated with the signal
that it takes place involuntarily, without any effort of
the will, the message goes from the eye to the hand
along the line E E B H. This may happen with a
practised performer when it is settled beforehand which
hand he is to use. But if it is necessary to deliberate
about the action, to call in the exercise of the will, the
message goes round the loop-line, E E C C B H ; from
the eye to the optic thalanii, from them to the cere-
brum, thence to the corpora striata, and so through the
medulla to the hand.

Besides this fact which we have just explained, the
fact of a message going from one part of the body to
the brain and coming out in the motion of some other
part of the body, there is another thing which is going
on continually, and that is this : There is a faint repro-
duction of some excitement which has previously existed
in the cerebral hemispheres, and which calls up, by the
process which we have just now described, all those
that have become associated with it ; and it is continu-
ally sending down faint messages which do not actually
tell the muscles to move, but which as it were begin to
tell them to move. They are not always strong enough
to produce actual motions, but they produce just the
beginnings of those motions : and that process goes on
even when there is apparently no sensation and no
motion. If a man is in a brown study, with his eyes
shut, although he apparently sees and feels nothing at
all, there is a certain action going on inside his brain
which is not sensation, but is like it, because it is the
transmission to the cerebral hemispheres of faint mes-
sages which are copies of previous sensations ; and it


loes not produce motion, but it produces something
like it ; it produces incipient motion, the beginnings of
motion which do not actually take effect. Sometimes a
train of thought may so increase in strength as to pro-
duce motion. A man may get so excited by a train of
thought that he jumps up and does something in con-
sequence. And the sensory impressions which are taken
from the ganglia to the hemispheres may be so strong
as to produce an illusion ; he may think that he sees
something, he may think that he sees a ghost, when he
does not. This continuous action of the brain depends
upon the presence of blood ; so long as the proper
amount of blood is sent to the brain it is active, and
when the blood is taken away it becomes inactive. And
it is a curious property of the nervous system that it can
direct the supply of blood which is to be sent to a parti-
cular part of it. It is possible, by directing your attention
to a particular part of your hand, to make a determina-
tion of blood to that part which shall in time become a
sore place. Some people have given this explanation,
which seems a very probable one, of what has happened
to those saints who have meditated so long upon the cru-
cifixion that they have got what are called stigmata, that
is, marks of wounds corresponding to the wounds they
were thinking about.

That, then, is the general character of the nervous
system which we have to consider in connexion with
the mind. There is a train of facts between stimulus
and motion which may be of two kinds : it may be
direct or it may be indirect, it may go round the loop-
line or not ; and also there is a continuous action of
the brain even when these steps are not taking place in


completeness. Moreover, when two actions take place
simultaneously, they form a sort of link between them,
so that if one of them is afterwards repeated the other
gets repeated with it. That is what we have to remem-
ber chiefly as to the character of the brain.

Now let us consider the other class of facts and the
connexions between them the facts of consciousness.
An eminent divine once said to me that he thought
there were only two kinds of consciousness to have a
feeling, and to know that you have a feeling. It
seems to me that there is only one kind of conscious-
ness, and that is to have fifty thousand feelings at once,
and to know them all in different degrees. Whenever
I try to analyse any particular state of consciousness in
which I am, I find that it is an extremely complex one.
I cannot help at this moment having a consciousness of
all the different parts of this hall, and of a great sea of
faces before me ; and I cannot help having the con-

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Online LibraryWilliam Kingdon CliffordLectures and essays by William Kingdon Clifford (Volume 2) → online text (page 3 of 22)