The Sun.
London, England, 1820-12-27 00:00:00

A NEW THEORY OF SENSATION.

MR. EDITOR—No theory that is MA in direct
opposition to common sense, should be withheld
from the public, because, even those that are
erroneous, by presenting objects in a new point of.
view, have frequently led to important discoveries,
and from the contact of opposite ideas, a spark
of truth may be often elicited. Actuated by these
motives, I take the liberty of sending to you the
following theory, leaving you to determine whe-
ther you think it deserves a place in your Paper.
I am, Sir, yeur's,
Paddington House. A.

'Every person who advances a new opinion upon what ha'
hero considered as well established facts, is immediately as-
sailed by numerons .objections, and surrounded by serious
difficulties. In the contest into Which he engages, he stands
alone, against a formidable array of ancient prejudices, the
remotral of which can he no very easy task ; but great as these.
obstacles may appear, they are not, perhaps, wholly insur-
mountable, and should not, therefore, discourage the man
whose ohject is the discovery of troth. However singular a
physical opinion may he, it cannot • be rejected as emmeous,
uniess it be in direct opposition to the laws of nature ; which,
I trust, is not the case with the idea I now advance, that man
has only one sense, via. Feeling,, of which, tasting, smelting,
hearing and seeing; are only different modifications. The
.conclusions drawn in support of this system, ale del ire(' :rum
these two well known axioms of the Newtonian Philosophy.
i. That no more causes most be admitted than are absolutely
necessary to explain an effect ; and ad, That similar effects
must be produced by one and the. same cause. The former
of these.akionts is-founded upon the acknowledged uniformity
"and simplicity of the Laws of Nature, stud the latter upon the
principles of analogy. Simplicity is indeed a great charac-
teristic of the operations cif nature; hence an infinite variety
of effects are often produced by a small number of causes.
hui, the vivid It that enliven the gardens, proceed only
fruits the refraction of, light, and all the musical tones that
delight the ear, are only modulations of sound.
Out: ideas of external objects arise from the action of these
objects upon our organs. This action ceases, whenever they,
are removed, or whenever -their'frce conontinication with our
organs is'itOpedea : and when it has c.easedS we can no longer
form any immediate notion of their different properties and
qualities. It is, therefore, evident, that no sensation can be
conveyed to the wind, unless there be a tree communication
between objects and our. organs: or, in short, that oily setis
sations arise front the action of bodies, or of their particles,
upon the nerves'destined to receive these impressiuos, and to
convey them to the mind. To prove that this operation is
wholly muchanieal, let its briefly examine how each of our
sensations are produced, and it in all of then) we perceive a
similarity of effect, they must he referred to a similar cause.
Tasting is occasioned by the contact of our food or drink
with the nerves of the palate and tongue. Smelling is caused
by the action-of the minute and volatile part fetes that ema-
nate from odorous bodies, upon the olfactory nerves. Hear-
ing is produced by the action of the pulses of sound upon the
tympanum of the ear. , Vision is caused by the action of the
rays of light upon the optic nerve. Feeling is occasioned by
the action, or contact, of bodies with .our organs of toitcl).
Heitce it appears, that every sensation is produced by the
action of external objects upon the nervous systeni. This
is evidently the case in respect to feeling and tasting; which
both require the actual contact of what is felt or tasted, with
the organs of touch and taste. But contact, is requisite also
to produce the sensations of scents, sound, and light and co-
lours. If the eye, nose or ear be stopped up, we no longer
see, smell, or hear, because the communication between the
rays of light, the effluvia of bodies, and the pulses of sound,
with the-organs of vision, sinelling and hearing is, interrupted.
Then why not say, that since .no sensation can he producedr
without the actual contact, or the action, of bodies, or of their
particles, upstu one organs, or, in short, unless these organs
feel those bodies, we have in fact only one sensation, viz.
touch, which exists under different modifications, and con-
veys to the mind different ideas, because it resides in different
organs ? Why not admit, that every sensation which cannot
be produced without actual contact with the nerves, which
are essentially the organs of touch, originate in touch only ?
Man is a sentient being; as such, he must necessarily be
MI feeling: and his other sensations, which ars incidental,
hut not necessary, to his existeoce, are lolly various modifi-
cations of this sole and uoiversal sense, transmitted indeed
to the mind through the medium of different organs. Being
so constituted that his enjoyments arise, in a great measure,
from the operation of external objects, man must possess a
consciousness of his existence, and of his identity, and touch
was given him for this purpose. Hence its organs are not
limited to any one part, but extend throughout the *hole of
his frame, and such is its intimate connection with his being—
that it begins at his birth, aced terminates only with his es-
istenie. The loss of taste, of suielling, of hearing, or of see-
ing, deprives him only of some enjoyments; but he ceases to
feel only when he ceases to exist.
Such is the resemblance between taste and touch that they
can hardly be considered as two distinct senses, since they dif-
fer only in the situation and not in the nature of their organs.
We can no more form any indea of the taste of a substance
unless it Noel' the palate, than of its baldness .or softness,
&c. unless it touch our hand or any part of our body.
The similarity between touch and smelling is not so evi-
dent, yet let us remember that we can form no idea of scents,
unless the odoriferous particles of bodies act or touch upon
our olfactory nerves. such is, however, the analogy between
smelling and tasting, which has been proved to lie only
touch, that it is often rather difficult to distinguish the one
.front the other; indeed most people must have remarked a
singular coincidence between the ideas which both these sen-
sations prodiice on the mind. Now, if these sensations be
only different modifications of touch, it cannot be surprishig,
that they should produce effects nearly analog ous, but
not exactly similar, because they are—conveyed to the sense-
. riunt, through the medium of different organs.
Although the analogy of hearing and vision with touch, be
not immediately obvious, I still hope to trace each of them
to the latter source. When the extreme simplicity of the or-
gan of touch is compated with thewonderful mechanism of the
eye and cif the ear ; it seems, indeed, difficult to admit at once
that the different sensations they produce originate in the
same cause. I may he asked immediately, how I can imagine
that instruments formed with so much skill and so admirably
adapted to produce the proposed effect, can be in fact, of no
sort of utility ? But I do not contend that our organs are use-
less, nor that we could either see, hear, taste, or smell, with-
out the organs of vision, hearingonsting, and smelling. On
the contrary, I maintain that without these, touch could not
he so modified as to produce in our mind five distinct species
of sensations; but, considering touch as the only source of
all our sensations, or as our only sense, I believe, that if it
were possible to acquire a notion of colours, forms, &c. with-
out eyes, it would be by touch only, of which vision is a mere
modification. It. is certain that this sense is mote acute in
blind persons, than in those whose vision is perfect. It is not
therefore absolutely impossible, that, in a person of great
nervous sensibility, touch should become so acute as to be
affected not only by the action of- the rays of light, but also
their refraction. Such a person, if born blind, could not in-
deed acquire our ideas of colours, but it is not impossible that
the different refraction of the rays of light by which tire va•
;ions colours are produced, should become so sensible to tine
touch of such a person" as 'to etitiv-ry tb its mind an idea-ot
the different manner in which colours affect the eyeS of those
that are blessed with vision.

Adopting the common opinion that man has five senses,
feeling, tasting, and smelling, may be termed sensual, and
seeing and hearing, intellectual senses; because the former
minister chiefly to the preservation and pleasures of the
body, and the latter to the enjoyments of the mind. These
are nndoubtedly the principal sources of our mental plea•
sures, and they are so remote from touch, that it must seem
difficult to prove their identity. Yet 1 believe that
we need only suppose, what is really the case, that
the, organs, by which touch is modified, are propor-
tionably delicate, and their mechanism proportionably
admirable. The sensations received by the eye and ear,
are more complicated, more varied, and embrace a wider
range than those communicated by the other organs ; and
the substances by which they are produced are of a more
delicate nature. Hence the organs must be also more skil-
fully contrived, and so formed as topetthe least icripiessions;
and this we find is the case in the eye, still more than in. the
car.

The organ of bearing is certainly wonderfully constructed,
and most admirably adapted to the performance of its object.
But I apprehend that its
.excellencies consist, not in its prU-
ducing a hew sense, so much as in its being funned so as to
prevent .t he air from acting too violently upon the auditory
'nerve. As we live in• the midst yf a light and elastic fluid,
which yields to tite ;past:impression, which is continually agi•
toted by innumerable. isugulses, and which is the medium of
sound, it was netessaty to consttuct the organ intended to-re-
ceive these impressions, and convey them to the mind, so
that each impression should be successive and distinct.
Hence the admirable but complicated machinery of the car.

The air agitated by every external impulse, acts upon the
organs of hearing, which are constructed all as to prevent this
action of the pulses of sound on the tympanum from being tuu
violent. Here we find that to produce.lhe sensation of sound,
the agitated air must operate upon the delicate membrane
Which Conveys the sensation to the mind ; and whenever the
comMunication between the air and the ear is interrupted,
so that the former cannot act on the latter, or the latter
cannot eel the former, no sensation of sound is
awakened in the mind. We find therefore that in hearing
as well as in feeling, salting, and swelling, the operation of
some substance on our nerves is requisite to produce a sen-
sation, and we may justly ask why effects so similar in their
nature should not be attributed to the same cause, namely
that of touch ?
The mechanism of the eye is no less wonderful than that of
the ear, and no less essential to the objects it has to accom-
plish. It is an accurate optical instrument, calculated, like
all double convex lenses, to collect the rays of light, to con-
verge them tow focus, and to increase the intensity of their
action. Light is so rare, that notwithstanding the amazing
rapidity of its motion, its momentum would he very inconst-
dei able. Hence the fibres on which it is to act, are of a very
delicate texture, anti its rays are collet:Ted by the crystalline
humour, and acquire force sufficient to cause a vibration of
the optic nerve. The sensation of light and of colours, is
therefore produced by theiriet ion of the•rays of light reflect-
ed or emitted from every external object upon the optic nerve :
and no such sensation can be produced, if any opaque sub-
stance be interposed between the eye, and the surrouud►ng
objects. In vision, then, the optic nerve twist feel the ac-
tion of light, just as in feeling, swelling, tasting, and hear-
ing, a contact between the organs of,these sensations, and
bodies or their particles are requisite to create in the mind an
idea of their qualities. In these five cases, the organs are
different, the sensations produced are distinct, but their
primary cause, or the source front whence they originate.,
the.satue. It is, like every other primary cause, simple in its
nature, but diversified in its effects, every one of which
hears the stamp of the sonice from whence it springs, and to
which it may he traced, how much soever it may be disguised.
Thus, at first sight, 'vision appears very remote from touch.
Yet, if the action of light he increased by means of a burn-
ing glass, the sensation would he changed front one of plea-
sure to one of pain, because the action of the rays of light
would be then too violent for the eye. But if a greater or a
lesser quantity of light can suddenly so change the nature of
our sensation as to produce pain instead of pleasure, is it not
more reasonable to conclude, that it is because the organs of
feeling adapted in the eye for the purposes of vision are acted
upon with too much violence when we feel pain, than to
imagine that the excess of light changes the nature of the
organ, and transforms it suddenly into an organ of touch, in-
stead of an organ of vision? The sensation of pain, which
Undoubtedly belongs to feeling, may he produced in every
one of our organi. Touch or feeling is allowed indeed to
reside ',in all our organs, and to pervade the whole of our
frame. It is therefore, avowedly, the n►ost universal of our
senses ; and this alone might create a suspicion.of its being
the only source of all our sensations, or lather our only sense
or sensation.

The idea of considering all our sensations as residing in
touch is not unnatural, since we find that all the colours are
only modifications of light, and all the tunes of music, modu-
lations of sound. These two facts prove, that a substance
may be modified so as to produce in the mind very different
impressions. And why should not. this be the case in respect
to our sensations ? '‘C by should not all our supposed senses
reside in touch, and appear different only when they reach
the mind through different organs ? It by no means neces-
sarily follows, that we ought to have only one organ, because
we have only one sense. On the contrary, we may easily
conceive, that the same sense may be as differently modified,
by means of different organs, as light when seen through va-
rious coloured glasses, of as sound modulated or agitated by
different iustruments. Touch was fully adequate to the iden-
tity and mere existence of man ; but to minister to his com-
forts, it was so modified as to produce all the sensations of
which he is susceptible. It is undoubtedly the most import-
ant, and we have shown that it is likewise the most universal,
of his supposed senses ; why nut therefore consider it as his
only sense ? -
By sense is meant only the medium through which different
sensations and perceptions are conveyed and awakened in the
Mind. But because these sensations and perceptions, and
indeed the organs through which we receive them, are differ-
ent, we ought nut to conclude, that they are nut produced by
the same cause, residing in distinct organs. We know that
touch takes place only in actual contact, without which ❑o
sensation can be possibly produced, But I have shown that
actual contact is also requisite to produce every one of our
sensations, whence I think myself justified in considering
them as effects of our cause, or as modifications of our sole
and universal sense, to which I give the name of sensation.—
am led to this conclusion by analogy; and I adopt it because
I find it consonant to the two principles which have been my
guides, and to the acknowledged simplicity of the operations
of nature, in which we unifolinly discover few Causes and
many effects.