advantages from that full knowledge which the experience of many years
has given, we purchase these by disadvantages which are perhaps as
great, and which are greater, from the very circumstance, that it is
absolutely out of our power to estimate their amount. What we consider
as the _immediate_ sensation, is not the simple mental state, as it
originally followed that corporeal change, which now precedes it; but,
at least in the most striking of all the tribes of our sensations, is
a very different one. We have the authority of reason, _a priori_, as
shewing no peculiar connexion of the points of the retina with one
place of bodies more than with another; and we have the authority
also of observation, in the celebrated case of the young man who was
couched by Cheselden, and in other cases of the same peculiar species
of blindness, in which the eyes, by a surgical operation, have been
rendered for the first time capable of distinct vision, that if we had
had no organ of sense but that of sight, and no instinctive judgment
had been superadded to mere vision, we should not have had the power
of distinguishing the magnitude and distant place of objects;--a mere
expanse of colour being all which we should have perceived, if even
colour itself could in these circumstances, have been perceived by us
as expanded. Yet it is sufficient now, that rays of light, precisely
the same in number, and in precisely the same direction, as those
which at one period of our life, exhibited to us colour, and colour
alone, should fall once more on the same small expanse of nerve, to
give us instantly that boundlessness of vision, which, almost as if the
fetters of our mortal frame were shaken off, lifts us from our dungeon,
and makes us truly citizens, not of the _earth_ only, but of the
_universe_. Simple as the principle may now seem, which distinguishes
our secondary or acquired perceptions of vision from those which were
primary and immediate, it was long before the distinction was made; and
till a period which--if we consider it in relation to those long ages
of philosophic inquiry, or, rather, most unphilosophic argumentation,
which had gone before--may be considered almost as in our own time,
longitudinal distance was conceived to be as completely an original
object of sight as the varieties of mere colour and brilliancy. There
may, therefore--though we have not yet been able, and may never be
able, to discover it,--be a corresponding difference in our other
sensations, which now seem to us simple and immediate. In the case of
sound, indeed, there is a very evident analogy to these visual acquired
perceptions; since a constant reference to _place_ mingles with our
sensations of this class, in the same manner, though not so distinctly,
as in our perceptions of sight. We perceive the sound, as it were near
or at a distance, in one direction rather than in another; as, in
the case of longitudinal distance in vision, we perceive _colour_ at
one distance rather than at another. Yet there is as little reason,
from the nature of the organic changes themselves, to suppose, that
different affections of our auditory nerves should _originally_ give us
different notions of distance, as that such notions should originally
be produced by different affections of the retina: and, as in sight
and hearing, so it is far from improbable, that, in all our senses,
there may, by the reciprocal influence of these upon each other, or by
the repeated lessons of individual experience in each, be a similar
modification of the original simple feelings, which, in that first
stage of existence that opened to us the world and its phenomena,
each individual organ separately afforded. Our reasoning with respect
to them, therefore, as original organs of sense, may, perhaps, be as
false, as our chemical reasoning would be, were we to attempt to infer
the properties of an uncombined acid, or alkali, from our observation
of the very different properties of a neutral salt, into the
composition of which we know that the acid or the alkali has entered.
If, indeed, it were in our power to be introduced to a society, like
that of which Diderot speaks, in his Letter on the Deaf and Dumb, and
to hold communication with them, all our doubts on this subject would
be removed. “What a strange society,” says he, “would five persons
make, each of them endowed with one only of our five different senses;
and no two of the party with the same sense! There can be no doubt,
that, differing, as they must differ, in all their views of nature,
they would treat each other as madmen, and that each would look upon
the others with all due contempt. It is, indeed, only an image of what
is happening every moment in the world; we have but one sense, and we
judge of every thing.”[63]--“There is, however,” he justly remarks,
“_one_ science, though but one science, in which the whole society of
the different senses might agree,--the science which has relation to
the _properties of number_. They might each arrive, by their separate
abstractions, at the sublimest speculations of arithmetic and algebra;
they might fathom the depths of analysis, and propose and resolve
problems of the most complicated equations, as if they were all so many
Diophantuses. It is perhaps,” he adds, “what the oyster is doing in its
shell.”[64]
From such a society,--if, indeed, we could hold any communication
with these profound algebraists, except in their common science of
numbers,--we might undoubtedly learn, what are the direct immediate
affections of mind, to which our senses individually give rise, and
consequently, how much, while feeling has blended with feeling,
they have reciprocally operated on each other. But, in our present
circumstances, unaided by intercourse with such living abstractions,
it is impossible for us to remove wholly this uncertainty, as to
the kind and degree of influence, which experience may have had, in
modifying our primary sensations. We may wish, indeed, to be able
to distinguish our _present_ feelings, from those which the same
objects _originally_ excited; but, since no memory can go back to
the period, at which we did not perceive longitudinal distance, as
it were, immediately by the eye, as little, we may suppose, can any
memory go back to the period, when other sensations, less interesting
than those of vision, were first excited. Could we trace the series of
feelings, in a single mind,--as variously modified, in the progress
from infancy to maturity,--we should know more of the intellectual
and moral nature of man, than is probably ever to be revealed to his
inquiry,--when in ages, as remote from that in which we live, and
perhaps as much more enlightened, as our own age may be said to be
in relation to the period of original darkness and barbarism, he is
still to be searching into his own nature, with the same avidity as
now, He must, indeed be a very dull observer, who has not felt, on
looking at an infant, some desire to know the little processes of
thought, that are going on in his curious and active mind; and who, on
reflecting on the value, as an attainment in science, which the sagest
philosopher would set on the consciousness of those acquisitions which
infancy has already made, is not struck with that nearness, in which,
in some points, extreme knowledge and extreme ignorance may almost
be said to meet. What metaphysician is there, however subtile and
profound in his analytical inquiries, and however successful in the
analyses which he has made, who would not give all his past discovery,
and all his hopes of future discovery, for the certainty of knowing
with exactness what every infant feels? The full instruction, which
such a view of our progressive feelings, from their very origin, in
the first sensations of life, would afford, Nature, in her wisdom,
however, has not communicated to us,--more than she has communicated
to us the nature of that state of being, which awaits the soul after
it has finished its career of mortality. Our existence seems, in our
conception of it, never to have had a beginning. As far back as we can
remember any event, there is always a period, that appears to us still
farther back, the events of which we cannot distinguish; as, when we
look toward the distant horizon, we see, less and less distinctly, in
the long line which the sunshine of evening still illuminates, plains,
and woods, and streams, and hills, more distant, half melting into air,
beyond which our eye can find nothing,--though we are still certain,
that other woods, and streams, and plains are there, and that it is
only the imperfection of our sight, which seems to bound them as in
another world. It is to man, when he thinks upon his own beginning,
as if he felt himself in a world of enchantment, amid the shades and
flowers of which he had been wandering, unconscious of the time at
which he entered it, or of the objects that are awaiting him, when he
shall have arrived at the close of that path, whose windings still lead
him forward,--and knowing little more, than that he is himself happy,
and that the unknown Being, who has raised this magnificent scene
around him, must be the Friend of the mortal, whom he has deigned to
admit into it.
“Well pleased he scans
The goodly prospect,--and, with inward smiles,
Treads the gay verdure of the painted plain,--
Beholds the azure canopy of heaven,
And living lamps, that over-arch his head,
With more than regal splendour,--bends his ear
To the full choir of water, air, and earth;
Nor heeds the pleasing error of his thought,
Nor doubts the painted green or azure arch,
Nor questions more the music's mingling sounds,
Than space, or motion, or eternal time;
So sweet he feels their influence to attract
His fixed soul, to brighten the dull glooms
Of care, and make the destined road of life
Delightful to his feet. So, fables tell,
The adventurous hero, bound on hard exploit,
Beholds with glad surprise, by secret spell
Of some kind sage, the patron of his toils,
A visionary paradise disclosed,
Amid the dubious wild;--With streams, and shades,
And airy songs, the enchanted landscape smiles,
Cheers his long labours, and renews his frame.”[65]
The philosophic use of the term _sensation_ does not necessarily
imply, what, in its popular use, is considered almost as involved
in it; and perhaps, therefore, it may not be superfluous to warn
you, that it is not confined to feelings, which are pleasurable or
painful, but extends to every mental affection, that is the immediate
consequence of impression on our organs of sense,--of which mental
states or affections, many, and, as I am inclined to think, by far the
greater number, are of a kind, that cannot be termed either agreeable
or disagreeable. Of the objects of sight, for example, which are
of such very frequent occurrence, how _few_ are there, at which we
look, either with pleasure or with pain,--if we except that indirect
pleasure, which, in particular cases, they may afford, as communicating
to us information, that is valuable in itself, or as gratifying even
our idlest curiosity. To take one of the most striking cases of this
sort,--though we may derive, from the perusal of a work that interests
us, the purest delight, it is a delight, resulting only from the
conceptions, which the author, in consequence of the happy contrivance
of symbolic characters, has been able to transfuse, as it were, from
his own mind into ours; but, during all the time of the perusal,
sensations, almost innumerable, have been excited in us, by the
separate characters, with which the pages are covered, that have never
mingled even the faintest direct pleasure, with the general emotion,
which they, and they alone, have indirectly produced.
“I apprehend,” says Dr Reid, “that, besides the sensations, that are
either agreeable or disagreeable, there is still a greater number that
are indifferent. To these we give so little attention, that they have
no name, and are immediately forgot, as if they had never been; and it
requires attention to the operations of our minds, to be convinced of
their existence. For this end, we may observe, that, to a good ear,
every human voice is distinguishable from all others. Some voices are
pleasant, some disagreeable; but the far greater part can neither
be said to be one or the other. The same thing may be said of other
sounds, and no less of tastes, smells, and colours; and if we consider,
that our senses are in continual exercise while we are awake, that some
sensation attends every object they present to us, and that familiar
objects seldom raise any emotion, pleasant or painful,--we shall see
reason, besides the agreeable and disagreeable, to admit a third class
of sensations, that may be called indifferent. The sensations that
are indifferent, are far from being useless. They serve as signs, to
distinguish things that differ; and the information we have concerning
things external, comes by their means. Thus, if a man had no ear to
receive pleasure from the harmony or melody of sounds, he would still
find the sense of hearing of great utility; though sounds gave him
neither pleasure nor pain, of themselves, they would give him much
useful information; and the like may be said of the sensations we have
by all the other senses.”[66]
It is as _signs_, indeed, far more than as mere pleasures in
themselves, that our sensations are to us of such inestimable value.
Even in the case to which I before alluded, of the symbolic or
arbitrary characters of a language, when we consider all the important
purposes to which these are subservient, as raising us originally from
absolute barbarism, and saving us from relapsing into it, there might
be an appearance of paradox, indeed, but there would be perfect truth
in asserting, that the sensations which are themselves indifferent,
are more precious, even in relation to happiness itself, than the
sensations which are themselves accompanied with lively delight, or
rather, of which it is the very essence to be delightful. Happiness,
though necessarily involving present pleasure, is the direct or
indirect, and often the very distant result of feelings of every
kind, pleasurable, painful, and indifferent. It is like the beautiful
profusion of flowers, which adorn our summer fields. In our admiration
of the foliage, and the blossoms, and the pure airs and sunshine, in
which they seem to live, we almost forget the darkness of the soil in
which their roots are spread. Yet how much should we err, if we were
to consider them as deriving their chief nutriment from the beams that
shine around them, in the warmth and light of which we have wandered
with joy. That delightful radiance alone would have been of little
efficacy, without the showers, from which, in those very wanderings, we
have often sought shelter at noon; or at least without the dews, which
were unheeded by us, as they fell silently and almost insensibly on our
evening walk.
With the common division of our sensations into five classes,--those
of smell, taste, hearing, sight, touch, we have been familiar, almost
from our childhood; and though the classification may be far from
perfect, in reference to our sensations themselves, considered simply
as affections of the mind, it is sufficiently accurate, in reference
to the mere organs of sense; for, though our sensations of _heat_
and _cold_, in one very important respect, which is afterwards to be
considered by us, have much less resemblance to the other sensations
which we acquire by our organs of touch, or at least to sensations,
which we are generally supposed to derive from that organ, than to
sensations, which we receive by the medium of other organs, our
sensations of smell and sound for example--still, as they arise from an
affection of the same organ, they may be more conveniently referred to
the same, than to any other class; since, if we quit that obvious line
of distinction, which the difference of organs affords, we shall not
find it easy to define them by other lines as precise.
But whatever may be the arbitrary division or arrangement which we
may form either of our sensations themselves, or of the organs that
are previously affected, the susceptibility of the mind, by which
it is capable of being affected by the changes of state in our mere
bodily organs, must be regarded as, in every sense of the word, of
primary value in our mental constitution. To the individual, indeed,
it may be said to be in itself all the things which are around him,
however near or afar; because it is truly that, by which alone all
things near or afar become known to him. It constitutes by this mutual
relation, which it establishes, a power of more than magic agency,
before which the great gulf, that appeared to separate forever the
worlds of matter and of spirit, disappears,--which thus links together
substances, that seemed, in their nature, incapable of any common bond
of union,--and which, bringing the whole infinity of things, within the
sphere of our own mind, communicates to it some faint semblance of the
omnipresence of its Author. “What is that organ,”--says an eloquent
French writer, speaking of the eye,--“what is that astonishing organ,
in which all objects acquire, by turns, a successive existence,--where
the spaces, the figures, and the motions, that surround me, are as
it were _created_,--where the stars, that exist at the distance of a
hundred millions of leagues, become a part of myself,--and where in a
single half inch of diameter, is contained the universe?” This power
of external sense, which first awakes us into life, continues, ever
after, to watch, as it were, round the life which it awoke, lavishing
on us perpetual varieties of instruction and delight; and if, from the
simple pleasures, and simple elementary knowledge which it immediately
affords, we trace its influence, through all the successive feelings
to which it indirectly gives rise, it may be said to exist, by a sort
of intellectual and moral transmutation, in the most refined and
etherial of all our thoughts and emotions. What Grey says of it,--in
the commencement of his beautiful fragment De Principiis Cogitandi,
addressed to his friend West, is not too high a panegyric,--that every
thing delightful and amiable, friendship and fancy, and wisdom itself,
have their primary source in it.
“Non illa leves primordia motus
Quanquam parva, dabunt. Lætum vel amabile quicquid
Usquam oritur, trahit hinc ortum; nec surgit ad auras,
Quin ea conspirent simul, eventusque secundent.
Hinc variæ vitai artes, ac mollior usus,
Dulce et amicitiæ vinclum: Sapientia dia
Hinc roseum accendit lumen, vultuque sereno,
Humanas aperit mentes, nova gaudia monstrans.
Illa etiam, quæ te (mirum) noctesque diesque
Assidue fovit inspirans, linguamque sequentem
Temperat in numeros, atque horas mulcet inertes,
Aurea non alia si jactat origine Musa.”[67]
So much, indeed, of human knowledge, and of all that is valuable and
delightful in human feeling, involves these elementary sensations, as
it were in the very essence of the thoughts and feelings themselves,
that one of the most acute of modern French metaphysicians, and, with
scarcely an exception, all the philosophers of the French metaphysical
school, who are his followers, have considered the whole variety of
human consciousness, as mere sensation variously transformed; though,
in stating the nature of this transformation, and the difference of
the sensations as transformed from the primary forms of mere external
feeling, they have not been so explicit, as the assertors of a system
so paradoxical ought assuredly to have been. On the fallacies of this
very prevalent theory of mind, however, which is afterwards to be
examined by us fully, I need not at present make any remarks.
Though this excessive simplification of the phenomena of human thought
and feeling is, however, far more than the phenomena truly allow, it
is not the less certain, that all the varieties of our consciousness,
though not mere _transformations_ of external sense, are, when traced
to their source, the _results_ of sensation, in its various original
forms. In inquiring into the phenomena of our senses, then, we begin
our inquiry, where knowledge itself begins, and though the twilight,
which hangs over this first opening of intellectual life, is perhaps
only a presage, or a part of that obscurity which is to attend the
whole track of human investigation, it still is twilight only, not
absolute darkness. We can discover _much_, though we cannot discover
_all_; and where absolute _discovery_ is _not_ allowed, there is still
left to us a probability of conjecture, of which, in such limited
circumstances, even philosophy may justly avail herself, without
departing from her legitimate province.
FOOTNOTES:
[63] Œuvres, tom. ii. p. 12.
[64] P. 131.
[65] Pleasures of Imagination, Book III. v. 493--514. The fixed soul,
v. 505. Exploits, v. 508; and Spells, v. 509. _Orig._
[66] On the Intellectual powers, Essay II. c. 16.
[67] Lib. I. v. 18-25. and 28-31.
LECTURE XIX.
BRIEF NOTICE OF THE CORPOREAL PART OF THE PROCESS, IN SENSATION.
The mental phenomena, of the class which is at present under our
consideration, being those, which arise, in consequence of certain
previous affections of our organs of sense, it is necessary, that we
should take some notice of the corporeal part of the process; though
it must always be remembered, that it is the last part of the process,
_the mental affection only_, which truly belongs to our science,--and
that, if this, in all its varieties, had been the result of any other
species of affections of organs constituted in any other manner,--as
long as there was the regular correspondence of certain mental
affections with certain organic affections,--the philosophy of mind
would have continued precisely the same as now. Our systems of anatomy,
and of the physiology of our mere bodily frame, would indeed have been
different,--but not that more intimate physiology, which relates to the
functions of the animating spirit, whose presence is life, and without
which our bodily frame, in all its beautiful adaptation of parts to
parts, is a machine, as inert and powerless, as the separate atoms that
compose it.
The great essential organ of all sensation is the _brain_, with its
appendages, particularly the _nerves_ that issue from it to certain
organs, which are more strictly termed the organs of sense; as it
is there the immediate objects, or external causes of sensation,
the particles of light, for example, in vision, or of odour in
smell, arrive, and come, as it were, into contact with the sensorial
substance. Each organ, as you well know, has objects peculiar to
itself, which it would be superfluous to enumerate; and since the
blind are still sensible of sound, the deaf of colour, and both of
smell, and taste, and touch, there must evidently be some difference,
either in the sensorial substance itself which is diffused over the
different organs, or in the mode of its diffusion and exposure in
the different organs, from which this striking diversity of their
relative sensibilities proceeds. The nervous matter however, considered
separately from the coats in which it is enveloped, is of the same
half-fibrous, but soft and pulpy texture, as the substance of the brain
itself, and is in perfect continuity with that substance, forming,
therefore, with it, what may be considered as one mass, as much as the
whole brain itself may be considered as one mass; which has, indeed,
for its chief seat the great cavity of the head; the
“Superas hominis sedes, arcemque cerebri;
Namque illic posuit solium, et sua templa sacravit,
Mens animi;--”[68]
but which extends, by innumerable ramifications, over the whole
surface, and through the internal parts of the body. The mind, in that
central brain in which it is supposed to reside, communicating with
all these extreme branches, has been compared, by a very obvious,
but a very beautiful similitude, to the parent Ocean, receiving from
innumerable distances the waters of its filial streams:
“Ac uti longinquis descendunt montibus amnes,
Velivolus Tamisis, flaventisque Indus arenæ,
Euphratesque, Tagusque, et opimo flumine Ganges,
Undas quisque suas volvens,--cursuque sonoro
In mare prorumpunt; hos magno acclinis in antro
Excipit Oceanus, natorumque ordine longo
Dona recognoscit venientum, ultroque serenat
Coeruleam faciem, et diffuso marmore ridet.
Haud aliter species properant se inferre novellæ
Certatim menti.”[69]