Thomas Reid.

The works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters online

. (page 32 of 114)
Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 32 of 114)
Font size
QR-code for this ebook

painters, or critics in painting, overlook
this ; and cannot easily be persuaded, that
the colour of the same object hath a dif-
ferent appearance at the distance of one
foot and of ten, in the shade and in the
light. But the masters in painting know
how, by the degradation of the colour and
the confusion of the minute parts, figures
which are upon the same canvass, and at
the same distance from the eye, may be
made to represent objects which are at the
most unequal distances. They know how
to make the objects appear to be of the
same colour, by making their pictures
really of different colours, according to
their distances or shades.

Secondly, Every one who is acquainted
with the rules of perspective, knows that
the appearance of the figure of the book
must vary in every different position : yet
if you ask a man that has no notion of
perspective, whether the figure of it does
not appear to his eye to be the same in all
its different positions ? he can with a good
conscience affirm that it does. He hath
learned to make allowance for the variety
of visible figure arising from the difference
of position, and to draw the proper con-
elusions from it. But he draws these con-
clusions so readily and habitually, as to lose
sight of the premises : and therefore where
he hath made the same conclusion, he con-
ceives the visible appearance must have
been the same.

Thirdly, Let us consider the apparent
magnitude or dimensions of the book.
Whether I view it at the distance of one
foot or of ten feet, it seems to be about
seven inches long, five broad, and one
thick. I can judge of these dimensions
very nearly by the eye, and I judge them
to be the same at both distances. But
yet it is certain, th:it, at the distance of

one foot, its visible length and breadth is
about ten times as great as at the distance
of ten feet ; and consequently its surface is
about a hundred times as great. This great
change of apparent magnitude is altogether
overlooked, and every man is apt to im-
agine, that it appears to the eye of the
same size at both distances. Further, when
1 look at the book, it seems plainly to have
three dimensions, of length, breadth, and
thickness : but it is certain that the visible
appearance hath no more than two, and
can be exactly represented upon a canvass
which hath only length and breadth.

In the last place, does not every man, by
sight, perceive the distance of the book
from his eye ? Can he not affirm with
certainty, that in one case it is not above
one foot distant, that in another it is ten ?
Nevertheless, it appears certain, that dis-
tance from the eye is no immediate object
of sight. There are certain things in the
visible appearance, which are signs of dis-
tance from the eye, and from which, as we
shall afterwards shew, we learn by experi-
ence to judge of that distance within cer-
tain limits ; but it seems beyond doubt,
that a man born blind, and suddenly made
to see, could form no judgment at first of
the distance of the objects which he saw.
The young man couched by Cheselden
thought, at first, that everything he saw
touched his eye,* and learned only by ex-
perience to judge of the distance of visible

I have entered into this long detail, in
order to shew that the visible appearance
of an object is extremely different from the
notion of it which experience teaches us to
form by sight ; and to enable the reader to
attend to the visible appearance of colour,
figure, and extension, in visible things,
which is no common object of thought, but
must be carefully attended to by those who
would enter into the philosophy of this
sense, or would comprehend what shall be
said upon it. To a man newly made to
see, the visible appearance of objects would
be the same as to us ; but he would see
nothing at all of their real dimensions, as
we do. He could form no conjecture, by
means of his sight only, bow many inches
or feet they were in length", breadth, or
thickness. He could perceive little or no-
thing of their real figure ; nor could hedis«
cern that this was a cube, that a sphere ;
that this was a cone, and that a cylinder.-|-

* Still they appeared external to the eye. — H.

f l his is a misinterpretation of Cheselden, on
whose authority this statement is made; though it
must be confessed that the mode in which the case of
the young man, couched by that distinguished sur-
fteon, is report d, no s not merit all the eulngia
that have been lavished on it. ;t is at once imper.
lect and indistinct. Thus, nn the point in questi<« •
Cheselden says;— "He (the patient) kne ? n« the
shape nt anything, • or uny one thing from a other.



His eye could not inform him that this
object was near, and that more remote.
The habit of a man or of a woman, which
appeared to us of one uniform colour, vari-
ously folded and shaded, would present to
his eye neither fold or shade, but variety of
colour. In a word, his eyes, though ever
so perfect, would at first give him almost no
information of things without him. They
would indeed present the same appearances
to him as they do to us, and speak the same
language ; but to him it is an unknown
language ; and, therefore, he would attend
only to the signs, without knowing the sig-
nification of them, whereas to us it is a lan-
guage perfectly familiar ; and, therefore,
we take no notice of the signs, but attend
only to the thing signified by them.

Section IV.


By colour, all men, who have not been
tutored by modern philosophy, understand,
not a sensation of the mind, which can have
no existence when it is not perceived, but a
quality or modification of bodies, which
continues to be the same whether it is seen
or not. The scarlet-rose which is before
me, is still a scarlet-rose when I shut my

however different In shape or magnitude; bu\ upon
being told what things were, whose form he before
knew from feeling, he would carefully observe, that
he might know them again ; but, > aving too many
objects to learn at once, he forgot many of them,
and (as he said) at first he learned to know, and again
forgot a thousand things in a day. One particular
only, though it may appear trifling, I will relate:
Having often forgot which whs the vat and which
the dog, he was ashamed to ask ; but, catching the
rat, which he knew by feeling, he was observed to
look at her steadfastly, and then, setiing her down,
*aid, *So, puss! I shall know yuu another time.'"

Here, when Cheselden says, " that his patient,
u hen iccently couched, knew not the shape of any
thing, nor anyone thing from another," &c , this
cannot mean that he saw no difference between
objects of different shapes and sizes; for, if this inter-
pretation were adopted, the rest <>i tie statement
beromes nonsense. If he had been altogether in ca-
llable of apprehending differences, it could not be
said that, " being told what things were whose form
he before knew from feeling, he would carefully
observe, that he might know them again;" for ob-
servation supposes the power of discrimination, and,
in particular, the anecdote of ihedog and cat would
be inconceivable on that hypothesis. It is plain that
Cheselden only meant to say, that the things which
the patient could previously distinguish and deno-
mina-eby touch, he could not now identity :md refer
ti> their appellations by sight Ami this is what we
might, a priori, be assured of. A sphere and a cube
would certainly make different impressions on him j
but it is probable that he could not assign to each its
name, though, in this particular cas-, there is gnod
ground for holding that the slightest consideration
would enable a person, previously acquainted with
these figures, and aware that the one was a cube
and the other a sphere, to connect them with his
anterior experience, and to discriminate them by
name,— See Fhilos. Trans., I "28, nu. 102.— H.

eyes, and was so at midnight when no eye
saw it. The colour remains when the
appearance ceases ; it remains the same
when the appearance changes. For when
I view this scarlet-rose through a pair of
green spectacles, the appearance is changed ;
but I do not conceive the colour of the rose
changed. To a person in the jaundice, it
has still another appearance ; but he is
easily convinced that the change is in his
eye, and not in the colour of the object.
Every different degree of light makes it
have a different appearance, and total dark-
ness takes away all appearance, but makes
not the least change in the colour of the
body. We may, by a variety of optical
experiments, change the appearance of
figure and magnitude in a body, as well as
that of colour; we may make one body
appear to be ten. But all men believe,
that, as a multiplying glass does not really
produce ten guineas out of one, nor a mi-
croscope turn a guinea into a ten-pound
piece, so neither does a coloured glass
change the real colour of the object seen
through it, when it changes the appearance
of that colour.

The common language of mankind shews
evidently, that we ought to distinguish be-
tween the colour of a body, which is con-
ceived to be a fixed and permanent quality
in the body, and the appearance of that
colour to the eve, which may be varied a
thousand ways, by a variation of the light,
of the medium, or of the eye itself. The
permanent colour of the body is the cause
which, by the mediation of various kinds or
degrees of light, and of various transparent
bodies interposed, produces all this variety
of appearances. When a coloured body is
presented, there is » certain apparition to
the eye, or to the mind, which we have
called the appearance of colt-ur, Mr Locke
calls it an idea ; and, indeed, it may be
called so with the greatest propriety. This
idea can have no existence but when it is
perceived. It is a kind of thought, and can
only be the act of a percipient or thinking
being. By the constitution of our nature,
we are led to conceive this idea as a sign of
something external, and are impatient till
we learn its meaning. A thousand experi-
ments for this purpose are made every day
by children, even before they come to the
use of reason. They look at things, they
handle them, they put them in various po-
sitions, at different distances, and in differ-
ent lights. The ideas of sight, by these
means, come to be associated with, and
readily to suggest, things external, and al-
together unlike them. In particular, that
idea which we have called the appearance
of colour, suggests the conception and belief
of some unknown quality in the body which
occasions the idea ; and it is to this quality,



and not to the idea, that we give the name
of colour.* The various colours, although
in their nature equally unknown, are easily
distinguished when we think or speak of
them, by being associated with the ideas
which they excite. In like manner, gravity,
magnetism, and electricity, although all
unknown qualities, are distinguished by
their different effects. As we grow up, the
mind acquires a habit of passing so rapidly
from the ideas of sight to the external
tilings suggested by them, that the ideas are
not in the least attended to, nor have they
names given them in common language.

When we think or speak of any parti-
cular colour, however simple the notion may
seem to be which is presented to the imagin-
ation, it is really in some sort compounded.
1 1 involves an unknown cause and a known
effect. The name of colour belongs indeed
to the cause only, and not to the effect.
But, as the cause is unknown, we can form no
distinct conception of it but by its relation to
the known effect ; and, therefore, both go to-
gether in the imagination, and are so closely
united, that they are mistaken for one simple
object of thought. +■ When I would conceive
those colours of bodies whkh we call scarlet
and blne—\i I conceived them only as un-
known qualities, I could perceive no distinc-
tion between the one and the other. I must,
therefore, for the sake of distinction, join to
each of them, in my imagination, some
effect or some relation that is peculiar ; and
the most obvious distinction is, the appear-
ance which one and the other makes to the
eye. Hence the appearance is, in the imagin-
ation, so closely united with the quality
called a scarlet-colour , that they are apt to
be mistaken for one and the same thing,
although they are in reality so different and
so unlike, that one is an idea in the mind,
the other is a quality of body.

I conclude, then, that colour is not a
sensation, but a secondary quality of bodies,
in the sense we have already explained;
that it is a certain power or virtue in bodies,
that in fair daylight exhibits to the eye an
appearance which is very familiar to us,
although it hath no name. Colour differs
from other secondary qualities in this, that,
whereas the name of the qualityis sometimes
given to the sensation which indicates it, and
is occasioned by it, we never, as far as I can
judge, give the name of colour to the sens-
ation, but to the quality only.J Perhaps

*+t It is justly observed by Mr Stewart, that
Ihp.-e p <ssages seem inconsistent with each other.
It in the perception of colour, the sensation and
the quality *< be so clo-ely united as to be mis-
taken lor one simp'e object of thought,** does it not
obviously follow, that it is to this compounded notion
the name of colour must in general be given ? On
the other hand, when it is said that the name of
co our is rtiver given to he sensation, hut to the
qualify only, does no 1 'his imply, that every time
the word is pronounced, the quality is separated from

the reason of this may be, that the appear-
ances of the same colour are so various and
changeable, according to the different mo-
difications of the light, of the medium, and
of the eye, that language could not afford
names for them. And, indeed, they are s-o
little interesting, that they are never at-
tended to, but serve only as signs to in-
troduce the things signified by them.
Nor ought it to appear incredible, that
appearances so frequent and so familiar
should have no names, nor be made ob-
jects of thought ; since we have before
shewn that this is true of many sensations of
touch, which are no less frequent nor less

Section V.


From what hath been said about colour,
we may infer two things. The first is, that
one of the most remarkable paradoxes of
modern philosophy, which hath been uni-
versally esteemed as a great discovery, is,
in reality, when examined to the bottom,
nothing else but an abuse of words. The
paradox I mean is, That colour is not a
quality of bodies, but only an idea in the
mind. We have shewn, that the word
colour, as used by the vulgar, cannot signify
an idea in the mind, but a permanent
quality of body. We have shewn, that
there is really a permanent quality of body,
to which the common use of this word ex-
actly agrees. Can any stronger proof be
desired, that this quality is that to which
the vulgar give the name of colour $ If it
should be said, that this quality, to which
we give the name of colour, is unknown to
the vulgar, and, therefore, can have no
name among them, I answer, it is, indeed,
known only by its effects — that is, by its
exciting a certain idea in us ; but are there
not numberless qualities of bodies which
are known only by their effects, to which,
notwithstanding, we find it necessary to
give names ? Medicine alone might fur-
nish us with a hundred instances of this
kind. Do not the words astringent, narcotic,
rpispasttc, caustic, and innumerable others,
s'gnify qualities of bodies, which are known
only by their effects upon animal bodies ?
Why, then, should not the vulgar give a
name to a quality, whose effects are every
moment perceived by their eyes ? We
have all the reason, therefore, that the
nature of the thing admits, to think that
the vulgar apply the name of co'our to that
quality of bodies which excites in us what

the sensation, even in the imagination of the vul
gat r-11.



the philosophers call the idea of colour.
And that that there is such a quality in
bodies, all philosophers allow, who allow that
there is any such thing as body. Philo-
sophers have thought fit to leave that
quality of bodies which the vulgar call
colour, without a name, and to give the
name of colour to the idea or appearance,
to which, as we have shewn, the vulgar
give no name, because they never make it
an object of thought or reflection. Hence
it appears, that, when philosophers affirm
that colour is not in bodies, but in the
mind, and the vulgar affirm that colour is
not in the mind, but is a quality of bodies,
there is no difference between them about
things, but only about the meaning of a

The vulgar have undoubted right to give
names to things which they are daily con-
versant about ; and philosophers seem
justly chargeable with an abuse of language,
when they change the meaning of a com-
mon word, without giving warning.

If it is a good rule, to think with philo-
sophers and speak with the vulgar, it must
be right to speak with the vulgar when we
think with them, and not to shock them by
philosophical paradoxes, which, when put
into common language, express only the
common sense of mankind.

If you ask a man that is no philosopher,
what colour is, or what makes one body
appear white, another scarlet, he can-
not tell. He leaves that inquiry to philo-
sophers, and can embrace any hypothesis
about it, except that of our modern philo-
sophers, who affirm that colour is not in
body, but only in the mind.

Nothing appears more shocking to his
apprehension, than that visible objects
should have no colour, and that colour
should be in that which he conceives to be
invisible. Yet this strange paradox is not
only universally received, but considered as
one of the noblest discoveries of modern
philosophy. The ingenious Addison, in
the Spectator, No. 413, speaks thus of it : —
" I have here supposed that my reader is
acquainted with that great modern discovery,
which is at present universally acknow-
ledged by all the inquirers into natural
philosophy — namely, that light and colours,
as apprehended by the imagination, are
only ideas in the mind, and not qualities
that have any existence in matter. As this
is a truth which has been proved incon-
testably by many modern philosophers, and
is, indeed, one of the finest speculations in
that science, if the English reader would see
the notion explained at large, he may find it
in the eighth chapter of the second book of
Locke's ' Essay on Human Understanding.' "

Mr Locke and Mr Addison are writers
who have deserved so well of mankind, that

one must feel some uneasiness in differing
from them, and would wish to ascribe all
the merit that is due to a discovery upon
which they put so high a value. And, in-
deed, it is just to acknowledge that Locke,
and other modern philosophers, on the sub-
ject of secondary qualities, have the merit
of distinguishing more accurately than those
that went before them, between the sensa-
tion in the mind, and that constitution or
quality of bodies which gives occasion to
the sensation. They have shewn clearly
that these two things are not only distinct,
but altogether unlike : that there is no
similitude between the effluvia of an odo-
rous body and the sensation of smell, or
between the vibrations of a sounding body
and the sensation of sound : that there can
be no resemblance between the feeling of
heat, and the constitution of the heated
body which occasions it; or between the
appearance which a coloured body makes to
the eye, and the texture of the body which
causes that appearance.

Nor was the merit small of distinguishing
these things accurately ; because, however
different and unlike in their nature, they
have been always so associated in the ima-
gination, as to coalesce, as it were, into one
two-faced form, which, from its amphibious
nature, could not justly be appropriated
either to body or mind ; and, until it was
properly distinguished into its different con-
stituent parts, it was impossible to assign to
either their just shares in it. None of the
ancient philosophers had made this distinc-
tion.* The followers of Democritus and
Epicurus conceived the forms of heat, and
sound, and colour, to be in the mind only ;
but that our senses fallaciously represented
them as being in bodies. The Peripatetics
imagined that those forms are really in
bodies; and that the images of them are
conveyed to the mind by our senses. +

The one system made the senses natur-
ally fallacious and deceitful ; the other
made the qualities of body to resemble the
sensations of the mind. Nor was it possible
to find a third, without making the distinc-
tion we have mentioned ; by which, indeed,
the errors of both these ancient systems are
avoided, and we are not left under the hard
necessity of believing, either, on the one
hand, that our sensations are like to the
qualities of body, or, on the other, that
God hath given us one faculty to deceive us,
and another to detect the cheat.

• This is inaccurate The distinction was known
to the ancient philosophers ; and Democritus was
generally allowed to be its author. This Reid himself
elsewhere indeed admits — (See above, p. 123, a ; a tl
p. 131, a)— H.

f These statements cr> oerning both classes ol

philosophers are vague and nu-orreit. Ihe Intter,

in general, only allowed sjiecifs for two sonars, Sight

a> <1 Hearing ; few admitted them in Feeling ; and

j some rejected the.n altogether. — H.



We desire, therefore, with pleasure, to
do justice to the doctrine of Locke, and
other modern philosophers, with regard to
colour and other secondary qualities, and
to ascribe to it its due merit, while we beg
leave to censure the language in which
they have expressed their doctrine. When
they had explained and established the dis-
tinction between the appearance which co-
lour makes to the eye, and the modifica-
tion of the coloured body which, by the
laws of nature, causes that appearance,
the question was, whether to give the
name of colour to the cause or to the ef-
fect ? By giving it, as they have done, to
the effect, they set philosophy apparently
in opposition to common sense, and expose
it to the ridicule of the vulgar. But had
they given the name of colour to the cause,
as they ought to have done, they must
then have affirmed, with the vulgar, that
colour is a quality of bodies ; and that
there is neither colour nor anything like
it in the mind. Their language, as well
as their sentiments, would have been per-
fectly agreeable to the common apprehen-
sions of mankind, and true Philosophy would
have joined hands with Common Sense.
As Locke was no enemy to common sense,
it may be presumed, that, in this instance,
as in some others, he was seduced by some
received hypothesis ; and that this was ac-
tually the case, will appear in the following

Section VI.


A second inference is, that, although co-
lour is really a quality of body, yet it is
not represented to the mind by an idea or
sensation that resembles it ; on the con-
trary, it is suggested by an idea which does
not in the least resemble it. And this in-
ference is applicable, not to colour only, but
to all the qualities of body which we have

It deserves to be remarked, that, in the
analysis we have hitherto given of the ope-
rations of the five seuses, and of the quali-
ties of bodies discovered by them, no in-
stance hath occurred, either of any sensation
which resembles any quality of body, or of
any quality of body whose image or resem-
blance is conveyed to the mind by means of
the senses.

There is no phsenomenon in nature more
unaccountable than the intercourse that is
carried on between the mind and the ex-
ter ,al world — there is no phsenomenon
which philosophical spirits have shewn

greater avidity to pry into, arid to resolve.
It is agreed by all, that this intercourse is
carried on by means of the senses ; and
this satisfies the vulgar curiosity, but not
the philosophic. Philosophers must have
some system, some hypothesis, that shews
the manner in which our senses make us

Online LibraryThomas ReidThe works of Thomas Reid, D.D.; now fully collected, with selections from his umpublished letters → online text (page 32 of 114)