Thomas Reid.

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

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either to the things themselves, (as the
omnipresent God is to the whole universe,)

• An error. Sec below, under p. 1 IB.— H.

+ That is, since the time of Erasistratusand Galen.
— H.

} Which is not the case. The Hypophysis, the
Vermiform process, &c, : re not less single than the
Conarium. — H.

§ See above, p. 2:14, b, note * — H.

|] Before Reid, these crude conjectures of Newton
were justly censured by Gcnove.-i. and oLtier.. — H.



[essay II,

or to the images of things, (as the soul of
man is in its proper sensory.) Nothing
can any more act, or be acted upon, where
it is not present, than it can be where it is
not. We are sure the soul cannot perceive
what it is not present to, because nothing
can act, or be acted upon, where it is not."

Mr Locke expresses himself so upon
this point, that, for the [101] most part,
one would imagine that he thought that
the ideas, or images of things, which he be-
lieved to be the immediate objects of per-
ception, are impressions upon the mind it-
self ; yet, in some passages, he rather
places them in the brain, and makes them
to be perceived by the mind there present.
" There are some ideas," says he, " which
have admittance only through one sense ;
and, if the organs or the nerves, which are
the conduits to convey them from without
to their audience in the brain, the mind's
presence room, if I may so call it, are so
disordered as not to perform their function,
they have no postern to be admitted by.

" There seems to be a constant decay of
all our ideas, even of those that are struck
deepest. The pictures drawn in our minds
are laid in fading colours. "Whether the
temper of the brain makes this difference,
that in some it retains the characters drawn
on it like marble, in others like freestone,
and in others little better than sand, I shall
not enquire."*

From these passages of Mr Locke, and
others of a like nature, it is plain that he
thought that there are images of external
objects conveyed to the brain. But whether
he thought with Des Cartes^ and Newton,
that the images in the brain are perceived
by the mind there present, or that they are
imprinted on the mind itself, is not so evi-

Now, with regard to this hypothesis,
there are three things that deserve to be
considered, because the hypothesis leans
upon them ; and, if any one of them fail, it
must fall to the ground. The first is, That
the soul has its seat, or, as Mr Locke calls
it, its presence room in the brain. The
second, That there are images formed in
the brain of all the objects of sense. The
third, That the mind or soul perceives these
images in the brain ; and that it perceives
not external objects immediately, but only
perceives them by means of those images.

As to the Jlrst point-^-that the soul has its

* No great stress should be laid on such figurative
passages as indications of the real opinion of .Locke,
which, on this point, it is not easy to discover. See
N-teO H.

+ Des Cartes is perhaps an erratum for Dr Clarke.
If not, the opinion of Des Cartes is misrepresented ;
for he denied to the mind all consciousness or imme-
diate knowledge of matter and its modifications.
But of this again, See Note N H.

seat in the brain — this, surely, is not so well
established as that we can safely build
other principles upon it. There have been
various opinions and -nuch disputation about
the place of spirits : whether they have a
place ? and, if they have, how they occupy
that place ? After men had fought in the
dark about those points for ages, the wiser
part seem to have left off disputing about
them, as matters beyond the reach of the
human faculties.

As to the second point — that images of all
the objects of sense are formed in the brain —
we may venture to affirm that there is no
proof nor probability of this, with regard to
any of the objects of sense ; and that, with
regard to the greater part of them, it is
words without any meaning."

We have not the least evidence that the
image of auy external object is formed in
the brain. The brain has been dissected
times innumerable by the nicest ana-
tomists ; every part of it examined by the
naked eye, and with the help of microscopes ;
but no vestige of an image of any external
object was ever found. The brain seems
to be the most improper substance that can
be imaginedfor receiving or retaining images,
being a soft, moist, medullary substance.

But how are these images formed ? or
whence do they come ? Says Mr Locke, the
organs of sense and nerves convey them from
without. This is just the Aristotelian
hypothesis of sensible species, which modern
philosophers have been at great pains to
refute, and which must be acknowledged to
be one of the most unintelligible parts of
the Peripatetic system. Those who con-
sider species of colour, figure, sound, and
smell, coming from the object, and entering
by the organs of sense, as a part of the
scholastic jargon long ago discarded from
sound philosophy, ought to have discarded
images in the brain along with them.
There never was a shadow of argument
brought by any author, to shew that an
[103] image of any external object ever
entered by any of the organs of sense.

That external objects make some impres-
sion on the organs of sense, and by them on
the nerves and brain, is granted ; but that
those impressions resemble the objects
they are made by, so as that they may be
called images of the objects, is most impro-
bable. Every hypothesis that has been
contrived, shews that there can be no such
resemblance ; for neither the motions of
animal spirits, nor the vibrations of elastic
chords, or of elastic tether, or of theinfinites-

* It 'would be rash to assume that, because a phi-
losopher uses the term image, or impression, or idea,
and places what it denotes in the brain, that he
therefore means that the mind was cognisant of such
corporeal affection, as ot its object, either in percep-
tion or imagination. See Note K.— H.





imal particles of the nerves, can be sup-
posed to resemble the objects by which
they are excited.

We know that, in vision, an image of the
visible object is formed in the bottom of the
eye by the rays of light. But we know,
also, that this image cannot be conveyed to
the brain, because the optic nerve, and all
the parts that surround it, are opaque and
impervious to the rays of light ; and there
is no other organ of sense in which any
image of the object is formed.

It is farther to be observed, that, with
regard to some objects of sense, we may
understand what is meant by an image of
them imprinted on the brain; but, with
regard to most objects of sense, the phrase
is absolutely unintelligible, and conveys no
meaning at all. As to objects of sight, I
understand what is meant by an image of
their figure in the brain. But how shall we
conceive an image of their colour where there
is absolute darkness ? And as to all other
objects of sense, except figure and colour,
I am unable to conceive what is meant by an
image of them. Let any man say what he
means by an image of heat and cold, an image
of hardness or softness, an image of sound,
or smell, or taste. The word image, when
applied to these objects of sense, has abso-
lutely no meaning. Upon what a weak
foundation, then, does this hypothesis stand,
when it supposes that images of all the
objects of sense are imprinted on the brain,
being conveyed thither by the conduits of the
organs and nerves ! * [104]

The third point in this hypothesis is,
That the mind perceives the images in the
brain, and external objects only by means
of them. This is as improbable as that
there are such images to be perceived. If
our powers of perception be not altogether
fallacious, the objects we perceive are not
in our brain, but without us.-)- We are so
far from perceiving images in the brain,
that we do not perceive our brain at all ;
nor would any man ever have known that
he had a brain, if anatomy had not dis-
covered, by dissection, that the brain is a
constituent part of the human body.

To sum up what has been said with re-
gard to the organs of perception, and the
impressions made upon our nerves and
brain. It is a law of our nature, estab-
lished by the will of the Supreme Being,
that we perceive no external object but by

* These objections to the hypothesis in question,
have been frequently urged both in ancient and in
modern tiroes. See Note K. — H.

t If this be taken literally and by itself, then, ac-
cording to Reid, perception is not an immanent cog-
nition; extension and figure are, in that act, not
merely suggested conceptions ; and, as we are perci-
pientof the non-ego, and, consciousof the perception,
we are therefore conscious of the non.ego. But 6ee
Note C— H.

£101, 105]

means of the organs given us for that pur-
pose. But these organs do not perceive.
The eye is the organ of sight, but it sees
not. A telescope is an artificial organ of
sight. The eye is a natural organ of sight,
but it sees as little as the telescope. We
know how the eye forms a picture of the
visible object upon the retina ; but how this
picture makes us see the object we know
not ; and if experience had not informed us
that such a picture is necessary to vision,
we should never have known it. We can
give no reason why the picture on the re.
tina should be followed by vision, while a
like picture on any other part of the body
produces nothing like vision.

It is likewise a law of our nature, that we
perceive not external objects, unless certain
impressions be made by the object upon the
organ, and by means of the organ upon the
nerves and brain. But of the nature of
those impressions we are perfectly ignorant ;
and though they are conjoined with percep-
tion by the will of our Maker, yet it does
not appear that they have any necessary con-
nection with it in their own nature, far less
that they can be the proper efficient cause
of it. [105] We perceive, because God has
given us the power of perceiving, and not
because we have impressions from objects.
We perceive nothing without those impres-
sions, because our Maker has limited and
circumscribed our powers of perception, by
such laws of Nature as to his wisdom seemed
meet, and such as suited our rank in his

* The doctrine of Reid and Stewart, in regard to
our perception of external things, bears a close ana-
logy to the Cartesian scheme of divine assistance, or
of occasional causes It seems, however, to coincide
most completely with the opinion of Ruardus Andala,
a Dutch Cartesian, who attempted to reconcile the
theory of assistance with that of physical infiuence
"Statuo," he says, "nos clarissimam et distinctissimam
hujus operationis et unionis posse habere ideam, si
modo, quod omnino facere oportet, ad Deum, caus-
sam ejus primam et liberam ascendamus, et ab ejus
beneplacito admirandum nunc effectum derivemus.
Nos possumus huic vel illi motui e. gr. campanas,
sic et hederas suspensas literis scriptis, verbis quibus-
cunque pronunciatie, aliisque signis, varias ideas
alligare, ita, ut per visum, vel auditum in mente ex-
citentur variee idea, perceptiones et sensationes .-
annon hinc clare et facile intellijn'mus, Deum crea-
toremm'ntis et corporiS'potuisse instituere et ordi.
nare, ut per vaiios in corpore motus varias in mente
excitentur ideas et perceptiones; et vicissim, ut pel
varias mentis volitiones, varii in corpore excitentur
ct producantur mctus r H nc et pro varia alter-
utrius partis dispositione altera pars variis modis
affici potest. Hoc autem a Deo ita ordinatum et
effectum esse, a posteriori, continua, certissima et
clarissima experientia docet Testes irrefragabiles
omnique exceptione maj'ires reciproci hujus com-
mercii, operationis mentis in corpus, et corporis in
mentem, nee non communionis status, sunt tensus
omnes turn externi, turn interni ; ut et omnes et
singula? et continual actiones mentis in corp-s, de
quibus modo fuit actum. Si quis vero a proprieta-
tibus mentis ad proprietates corporis progredi velit,
aut exraafarfldiversissimarum harum substantiarum
deductre motum in corpore, & perceptiones in mente,
aut hos effectus ut necessano connexns spectare ;
nffi is frustra erit, nihil intelliget, perveisissimephi







In speaking of the impressions made on
our organs in perception, we build upon
facts borrowed from anatomy and physio-
logy, for which we have the testimony of
our senses. But, being now to speak of
perception itself, which is solely an act of
the mind, we must appeal to another
authority. The operations of our minds
are known, not by sense, but by conscious-
ness, the authority of which is as certain
and as irresistible as that of sense.

In order, however, to our having a distinct
notion of any of the operations of our own
minds, it is not enough that we be conscious
of them ; for all men have this consciousness.
It is farther necessary that we attend to them
while they are exerted, and reflect upon them
with care, while they are recent and fresh
in our memory. It is necessary that, by
employing ourselves frequently in this way,
we get the habit of this attention and reflec-
tion ; and, therefore, for the proof of facts
which I shall have occasion to mention upon
this subject, I can only appeal to the reader's
own thoughts, whether such facts are not
agreeable to what he is conscious of in his
own mind. [106]

If, therefore, we attend to that act of
our mind which we call the perception of an
external object of sense, we shall find in it
these three things : — First, Some con-
ception or notion of the object perceived j
Secondly, A strong and irresistible convic-
tion and belief of its present existence ; and,
Thirdly, That this conviction and belief are
immediate, and not the effect of reasoning.*

First, It is impossible to perceive an
object without having some notion or con-
ception of that which we perceive. We
may, indeed, conceive an object which we
do not perceive ; but, when we perceive the
object, we must have some conception of it
at the same time ; and we have commonly
a more clear and steady notion of the object
while we perceive it, than we have from
memory or imagination when it is not per-
ceived. Yet, even in perception, the notion
which our senses give of the object may be
more or less clear, more or less distinct, in
all possible degrees.

Thus we see more distinctly an object at
a small than at a great distance. An object
at a great distance is seen more distinctly in

losophabitur nullamque hujus rei ideam habere po-
tent. Si vero ad Deum Creatorem adscendamus,
cumque vere agnoscamus, nihil hie erit obscuri,
nunc effectual clarissime intelligemus, et quidem per
eaussam ejus primam ; qua? perfectissima demum
est scientia." — H.

* See above, p. 183, a, noto < : p. 128. b, note » ;
and Note C— H.

a clear than in a foggy day. An object
seen indistinctly with the naked eye, on
account of its smallness, may be seen dis-
tinctly with a microscope. The objects in
this room will be seen by a person in the
room less and less distinctly as the light of
the day fails; they pass through all the
various degrees of distinctness according to
the degrees of the light, and, at last, in
total darkness they are not seen at all.
What has been said of the objects of sight
is so easily applied to the objects of the
other senses, that the application may be
left to the reader.

In a matter so obvious to every person
capable of reflection, it is necessary only
farther to observe, that the notion which
we get of an object, merely by our external
sense, ought not to be confounded with that
more scientific notion which a man, come to
the years of understanding, may have of the
same object, by attending to its various
attributes, or to its various parts, and their
relation to each other, and to the whole.
[107] Thus, the notion which a child has of
a jack for roasting meat, will be acknowledged
to be very different from that of a man who
understands its construction, and perceives
the relation of the parts to one another, and
to the whole. The child sees the jack and
every part of it as well as the man. The
child, therefore, has all the notion of it
which sight gives ; whatever there is more
in the notion which the man forms of it,
must be derived from other powers of the
mind, which may afterwards be explained.
This observation is made here only that we
may not confound the operations of differ-
ent powers of the mind, which by being
always conjoined after we grow up to under-
standing, are apt to pass for one and the same.

Secondly, In perception we not only have
a notion more or less distinct of the object
perceived, but also an irresistible conviction
and belief of its existence. This- is always
the case when we are certain that we per-
ceive it. There may be a perception so
faint and indistinct as to leave us in doubt
whether we perceive the object or not.
Thus, when a star begins to twinkle as the
light of the sun withdraws, one may, for a
short time, think he sees it without being
certain, until the perception acquire some
strength and steadiness. When a ship just
begins to appear in the utmost verge of the
horizon, we may at first be dubious whether
we perceive it or not ; but when the percep-
tion is in any degree clear and steady, there
remains no doubt of its reality ; and when
the reality of the perception is ascertained,
the existence of the object perceived can no
longer be doubted.*

• In this paragraph there is a confusion of that
which is perceived and that which is inferred from
the perception.— H.

fl06. 1071

f-HAP. V.]



By the laws of all nations, in the most
solemn judicial trials, wherein men's for-
tunes and lives are at stake, the sentence
passes according to the testimony of eye or
ear witnesses of good credit. An upright
judge will give a fair hearing to every objec-
tion that can be made to the integrity of a
witness, and allow it to be possible that he
may be corrupted ; but no judge will ever
suppose that witnesses maybe imposed upon
by trusting to their eyes and ears. And if
a sceptical counsel should plead against the
testimony of the witnesses, that they had
no other evidence for what they [108] de-
clared but the testimony of their eyes and
ears, and that we ought not to put so much
faith in our senses as to deprive men of life
or fortune upon their testimony, surely no
upright judge would admit a plea of this
kind. I believe no counsel, however scep-
tical, ever dared to offer such an argument ;
and, if it was offered, it would be rejected
with disdain.

Can any stronger proof be given that it
is the universal judgment of mankind that
the evidence of sense is a kind of evidence
which we may securely rest upon in the
most momentous concerns of mankind ;
that it is a kind of evidence against which
we ought not to admit any reasoning j and,
therefore, that to reason either for or against
it is an insult to common sense ?

The whole conduct of mankind in the
daily occurrences of life, as well as the so-
lemn procedure of judicatories in the trial
of causes civil and criminal, demonstrates
this. I know only of two exceptions that
may be offered against this being the uni-
versal belief of mankind.

The first exception is that of some luna-
tics who have been persuaded of things that
seem to contradict the clear testimony of
their senses. It is said there have been
lunatics and hypochondriacal persons, who
seriously helieved themselves to be made of
glass ; and, in consequence of this, lived in
continual terror of having their brittle frame
shivered into pieces.

All I have to say to this is, that our
minds, in our present state, are, as well as"
our bodies, liable to strange disorders ; and,
as we do not judge of the natural constitu-
tion of the body from the disorders or dis-
eases to which it is subject from accidents,
so neither ought we to judge of the natural
powers of the mind from its disorders, but
from its sound state. It is natural to man,
and common to the species, to have two
hands and two feet ; yet I have seen a man,
and a very ingenious one, who was born
without either hands or feet. [109] It is
natural to man to have faculties superior to
those of brutes ; yet we see some indivi-
duals whose faculties are not equal to those
cf many brutes ; and the wisest man may,

by various accidents, be reduced to this
state. General rules that regard those
whose intellects are sound are not over-
thrown by instances of men whose intellects
are hurt by any constitutional or accidental

The other exception that may be made
to the principle we have laid down is that
of some philosophers who have maintained
that the testimony of sense is fallacious,
and therefore ought never to be trusted.
Perhaps it might be a sufficient answer to
this to say, that there is nothing so absurd
which some philosophers have not main-
tained.* It is one thing to profess a doc-
trine of this kind, another seriously to be-
lieve it, and to be governed by it in the
conduct of life. It is evident that a man
who did not believe his senses could not
keep out of harm's way an hour of his life ;
yet, in all the history of philosophy, we
never read of any sceptic that ever stepped
into fire or water because he did not believe
his senses, or that shewed in the conduct of
life less trust in his senses than other men
have.-f This gives us jnst ground to appre-
hend that philosophy was never able to
conquer that natural belief which men have
in their senses ; and that all their subtile
reasonings against this belief were never
able to persuade themselves.

It appears, therefore, that the clear and
distinct testimony of our senses carries'
irresistible conviction along with it to everj
man in his right judgment.

I observed, Thirdly, That this conviction
is not only irresistible, but it is immediate
that is, it is not by a train of reasoning
and argumentation that we come to be
convinced of the existence of what we
perceive ; we ask no argument for the
existence of the object, but that we per-
ceive it ; perception commands our belief
upon its own authority, and disdains to
rest its authority upon any reasoning what-
soever. J [110]

The conviction of a truth may be irre-
sistible, and yet not immediate. Thus, my
conviction that the three angles of every
plain triangle are equal to two right angles,
is irresistible, but it is not immediate ; I
am convinced of it by demonstrative rea-
soning. There are other truths in mathe-
matics of which we have not only an irre-
sistible but an immediate conviction. Such
are the axioms. Our belief of the axioms
m mathematics is not grounded upon argu-

* A saying of Varro. — H.

t All this we read, however, in Laertius, of Pyrrho ;
and on the authority of Antigonus Carystius, the
great sceptic's contemporary. Whether we are to
believe the narrative is another question.— H.

X If Rcid holds that in perception we have only a
conception of the Non.Ego in the Ego,-th\s iielief is
either not the reflex of a cognition, but- a blind faith,
or it is mediate, as held by Stewart.— Phiio;. Ess. ii
c.2.— H.




[essay n.

ment — arguments are grounded upon them ;
but their evidence is discerned immediately
by the human understanding.

It is, no doubt, one thing to have an
immediate conviction of a self-evident
axiom ; it is another thing to have an im-
mediate conviction of the existence of what
we see ; but the conviction is equally imme-
diate and equally irresistible in both cases.
No man thinks of seeking a reason to believe
what he sees ; and, before we are capable of
reasoning, we put no less confidence in our
senses than after. The rudest savage is as
fully convinced of what he sees, and hears,
and feels, as the most expert logician. The
constitution of our understanding deter-
mines us to hold the truth of a mathematical
axiom as a first principle, from which other
truths may be deduced, but it is deduced
from none; and the constitution of our
power of perception determines us to hold
the existence of what we distinctly perceive
as a first principle, from which other truths

may be deduced ; but it is deduced fronK .fitted our powers of perception to this

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