know that he has a bodily frame, or a single organ of that frame, more
than he can know, that there are other bodies in nature, that act upon
his own; and we are not entitled to suppose,--however difficult it may
be for us to accommodate our supposition to the true circumstances of
the case,--that because _we_, the inquirers, know, that external bodies
are pressing on his organ of touch, the little sensitive being is to
have any knowledge, but of the mental affections, which these external
bodies excite. How the knowledge of any thing more than his own mind is
acquired, is, in truth, the very difficulty, which it is our labour to
solve.
In conformity with this view, then,--when we look on the infant,--one
of the most remarkable circumstances, which strike us, is its tendency
to use its muscles, with almost incessant exercise, particularly the
muscles of those parts, which are afterwards its principal organs
of measurement. Its little fingers are continually closing and
opening, and its little arms extending and contracting. The feelings,
therefore,--whatever these may be,--which attend the progressive
contraction of those parts,--and some feeling unquestionably attends
the contraction in all its stages,--must be continually arising in its
mind, beginning and finishing, in regular series, and varying exactly,
with the quantity of the contraction.
A _succession_ of feelings, however, when remembered by the mind, which
looks back upon them, we found to involve, necessarily, the notion of
divisibility into separate parts, and, therefore, of length, which is
only another name for continued divisibility. Time, in short, is to
our conception, a series in constant onward progress, and cannot be
conceived by us, but as a progressive series, of which our separate
feelings are parts; the remembrance of the events of our life, whenever
we take any distant retrospect of them, being like the remembrance
of the space, which we have traversed in a journey,--an indistinct
continuity of length, as truly divisible, in our conception, into the
separate events which we remember, as the space, which we remember to
have traversed, into its separate variety of scenes.
_Time_, then, or remembered succession, we found to involve, not
metaphorically, as is commonly said, but truly and strictly, in its
very essence, the notions of length and divisibility,--the great
elements of extension; and whatever other feelings may be habitually
and uniformly associated with these, will involve, of course, these
elementary notions.
The series of muscular feelings, of which the infant is conscious,--in
incessantly closing and opening his little hand,--must, on these
principles, be accompanied with the notion,--not, indeed, of the
existence of his hand, or of any thing external,--but of a certain
length of succession; and each stage of the contraction, by frequent
renewal, gradually becomes significant of a particular length,
corresponding with the portion of the series. When any hard body,
therefore, is placed in the infant's hand,--though he cannot, indeed,
have any knowledge of the object, or of the hand,--he yet feels, that
he can no longer perform the accustomed contraction,--or, to speak
more accurately,--since he is unacquainted with any parts that are
contracted, he feels, that he can no longer produce his accustomed
series of feelings; and he knows the quantity of contraction, which
remained to be performed, or rather the length of the series, which
remained to be felt. The place of this remaining length is now supplied
by a new feeling, partly muscular, and partly the result of the
affection of the compressed organ of touch,--and is supplied by the
same feeling, at the same point of the series, as often, as he attempts
to renew the contraction, while the body remains within his hand. The
_tactual feeling_, therefore,--whatever it may be,--becomes, by this
frequent repetition, associated with the notion of that particular
progressive series, or length, of which it thus uniformly supplies the
place; and at last becomes representative of this particular length,
precisely in the same manner, as, in the acquired perceptions of
vision, certain shades of colour become representative of distance, to
which they have, of themselves, no resemblance or analogy, whatever;
and we thus learn to feel length, as we learn to see length,--not
directly by the mere affections of our tactual or visual organs, but by
the associated notions which they suggest.
If _time_,--as perceived by us in the continued series of our
feelings,--do involve conceptual length and divisibility, it seems,
indeed, scarcely possible, that, in the circumstances supposed, the
notions supposed should not arise,--that the infant should be conscious
of a regular series of feelings, in the contraction of its fingers
and arms, and yet that portions of this series should not become
significant of various proportional lengths;--and, if the notion of
certain proportional lengths do truly accompany certain degrees of
progressive contraction, it seems equally impossible, according to
the general principles of our mental constitution, that the compound
tactual and muscular feeling, which must arise in every case, in which
any one of these degrees of contraction is impeded, should not become
associated with the notion of that particular length, of which it
supplies the place, so as at last to become truly representative of it.
In this manner, I endeavoured to explain to you, how our knowledge
of the mere length of bodies may have been acquired, from varieties
of length that are recognized as coexisting and proximate, and
are felt to unite, as it were, and terminate in our sensation of
resistance, which interrupts them equally, and interrupts always a
greater number of the coexisting truths, in proportion to the size
of the body compressed; and, in a similar manner, our notions of the
other dimensions of bodies, which are only these varieties of length
in different directions. I cannot conclude this summary, however,
without recalling to your attention, a very simple experiment, which
I requested you to make for yourselves,--an experiment, that, even in
the unfavourable circumstances in which it must now be tried, is yet,
I conceive, demonstrative of the influence of mere time, as an element
of that complex notion, which we have been examining, when the more
rapid measurements of vision,--which are confessedly not original but
acquired,--are excluded. If, in passing our finger, with different
degrees of slowness or rapidity, along the same surface, with our eyes
shut,--even though we should previously know the exact boundaries
of the extent of surface,--we feel it almost impossible not to
believe,--and but for the contrary evidence of vision, could not have
hesitated a single moment in believing,--that this extent is greater
or less, according as the time employed in performing exactly the same
quantity of motion, with exactly the same force of pressure, on the
same quantity of our organ of touch, may have been greater or less,--it
must surely be admitted, that the notion of the length, which thus
uniformly varies with the time, when all other circumstances are the
same, is not absolutely independent of the time,--or it must, in like
manner, be believed, that our notion of visual distance, which varies
with the distribution of a few rays of light on the small expanse of
the optic nerve, is yet independent of those faint shades of colouring,
according to the mere varieties of which, it seems at one time to lay
open to our view a landscape of many miles, and at another time to
present to us, as it were before our very eyes, an object of scarcely
an inch in diameter. The greater dimness, and diminished size of a
few objects in the back ground of a picture, which is in itself one
coloured plane of light, does not more truly seem to increase the line
of distance of those objects, than, in the other case, the increased
slowness of the motion of our hand along any surface, seems to lengthen
the line which separates one of its boundaries from the other.
That we now seem to perceive extension, immediately by _touch_, cannot
be denied; and, in a case so obscure as this,--with our very limited
knowledge, and our very limited power of adding to this knowledge,--it
may seem the most prudent, and perhaps even the most suitable,--as
it is, without all question, by far the easiest part,--to acquiesce
in the opinion, that the perception, which now seems immediate,
was so originally,--that the belief of the presence of an external
figured body, is, by the very constitution of our nature, attached
to a certain affection of the mere organ of touch. But, since there
are circumstances,--as we have seen,--which show this opinion, when
very nicely examined, to be inadmissible, we may, at least, attempt
to proceed a little farther, if we do this with a sufficient sense of
the very great difficulty of the attempt, in relation to our power
and knowledge, and consequently with a very humble assurance, as to
the certainty of any opinion which we may be led to form. To know the
mind _well_, is to know its _weaknesses_ as well as its _powers_;
and it is precisely in a case of this sort, that he, whose knowledge
is least imperfect, will be the best judge of its imperfection, and,
therefore, the least disposed to put complete reliance on it in his
own speculations,--or to assert it dogmatically, when he offers it, as
all opinions, on so very obscure a subject, should be offered, to the
inquiry, rather than to the undoubting assent.
The analysis, I own, is one which must require a considerable effort of
attention on your part, because it is truly one of the most subtile
on which I could call you to enter. But you must be aware, that this
subtlety is in the nature of the very inquiry itself; since it is
an inquiry into the elements and progressive growth of feelings,
which seem to us, at present, simple and immediate, and that the
alternatives, therefore, are not those of greater or less subtlety and
refinement of analysis, but of attempting the analysis, or abandoning
it altogether.
Before proceeding farther, in our inquiry with respect to the origin of
the notion of extension, it may, however, be of advantage, to take a
short retrospect of the progress which we have already made; for, if we
have found nothing more, we have, at least, as I conceive, found reason
to reject a considerable part of our former belief on the subject,
which, though a negative acquisition, is yet a very important one.
Though we should not be able to discover the true source of the notion
which we seek, it is something, at least, to know, that we have little
reason to expect to find it, where we have uniformly been accustomed to
seek it.
In the first place, then, we have seen the fallacy of the supposition,
that our knowledge of extension may be easily accounted for, by the
similarity in figure of the compressed part of the organ of touch to
the compressing body, since the notion of extension is not a state of
the material organ, compressed and figured, which, as mere matter,
however exquisitely organized, is as little capable of this notion,
as of smell, or taste, love or aversion, but, a state of the _mind
itself_, which is susceptible of shape or pressure, being as little
square, when it perceives a square, as when it perceives a circle; and
any affection of which, therefore, may be supposed as much to follow
any one shape, as any other shape of the mere external organ. If,
indeed, as this explanation most strangely seems to assume, we could
be supposed to have any previous knowledge of the shape of our organ
of touch, nothing more would be necessary, for we should then have
a perfect knowledge of extension, though no other extended body but
our own organ of touch were in existence. To refer us to the organ
is, however, only to bring the very same difficulty one step nearer,
since previously to the application of an external body, the mind has
as little knowledge of the shape of its organ of touch, as it has of
the body compressing it; and it is manifestly most absurd, to ascribe
the origin of our knowledge of extension, to our knowledge of the
resemblance in figure of an external body to our organ; since this
very knowledge of the resemblance must imply the previous knowledge of
the figure of both, and consequently of _that very extension_, which,
according to this supposition, must be known to us BEFORE it is known.
In the second place, we have seen, that, if the configuration of the
sensorial organ were the only circumstance necessary, to induce,
immediately, in mind, the notion of figure, this notion should
accompany every sensation of every kind; the smell of a rose, for
example, as much as the pressure of a cube or a sphere: for the nervous
expansion, in the organ of smell, and in every other organ, is of a
certain figure, _before_ sensation, _during_ sensation, and _after_
sensation, as much as the nervous expansion of the organ of touch. And,
though we were to confine ourselves wholly to this organ, the nervous
matter in it is, at all times, of a certain shape, as much when there
is no pressure on it, as when it is exposed to such pressure; yet the
mere figure of the organ of touch, is not then accompanied with the
mental notion of its figure; nor is this the case, merely when the
sense is quiescent, but, in many cases, in which it is affected in the
most lively manner; as, for example, when we are exposed to great cold
or heat, in which cases, the shape of this very tactual organ, thus
strongly affected, is as much unperceived by us, as when there is no
affection of it whatever.
Lastly, which is a point of much more importance, because it has
relation to the only philosophic view of touch, as the immediate
organ of extension; the view, in which the mere configuration of
the compressed organ, as similar to that of the compressing body,
is laid out of account, and the immediate belief of extension is
supposed to depend on the original constitution of the mind, by which
its affections have been arranged, so as to correspond with certain
affections of the bodily organs; the mental state which constitutes
the perception of a _square_, arising immediately when the organ of
touch is affected, in a certain manner, as that mental state which
constitutes the sensation of the fragrance of a _rose_, arises
immediately, when the organ of smell is affected, in a certain manner;
this opinion too, philosophic as it is, compared with those which we
before considered, though, in truth, it only assumes the point in
question, without attempting to solve any difficulty, supposed to be
connected with it, we have yet found to be as little tenable, as the
opinions that suppose the mental notion of figure to depend on the
peculiar figure of the compressed material organ. The consideration
which, as I stated in my last Lecture, seems to me decisive on this
point, is, that, if touch inform us of extension immediately, as
smell informs us of fragrance, sight of colour, and hearing of sound;
it must do this in every instance, without relation to particular
figure, as smell, sight, and hearing, extend to all odours, hues, and
sounds; for it would certainly be, as I said, a very strange abuse
of the license of supposition, to imagine that we perceive a square
immediately by touch, but not a circle; or a circle, but not a square;
or any one figure, but not any other figure. In short, if figure be the
direct primary object of touch, as sight is of vision, we should feel
immediately every form impressed, as we see immediately every colour.
It is only when the figures are very simple and regular, however, such
as we might be supposed to have easily learned, in the same manner
as we learn, visually, to judge of distances, that we are able to
discover them, as it were, immediately, by touch; and, even when we
are able, in this manner, to determine the _species of figure_, that
is to say, the mere outline of a body, we are rarely able to determine
the exact magnitude which that outline comprehends; yet, as our organ
must be affected by each part of the compressing surface, by the
central parts, as much as by the exterior parts which form its outline,
and by these, as much as by the central parts; and as every feeling
which the organ directly affords, must be immediate, when there is no
change of the position, or other circumstances of the object, that
might vary the sensation, we should, if mere touch communicated to us
the knowledge supposed, be able to determine, exactly and instantly,
the magnitude and figure; or, it is evident, that the determination
of magnitude and figure must depend wholly, or in part, on something
that is different from touch. The magnitude we are far from being able
to discover exactly, even of simple figures; and when the form is
very irregular, and we know nothing more, than that a certain body is
pressed against our hand,--the magnitude and figure are alike difficult
to be discovered; so difficult, that I may safely say, that no one, who
makes the experiment, will find, on opening his eyes, that his tactual
or intellectual measurement has, in any one case, been exact, or his
notion of the figure half so distinct as it now is, after a single
glance. Can we then think that it is by mere touch we discover figure,
as exactly as by the glance of our mature vision,--that we discover
it, in all its varieties, originally by touch, and as accurately at
first, as after innumerable trials,--when we discover it, only in a
few cases, that are previously familiar to us, and even in these very
imperfectly? The _determination_ of the form impressed, in which we are
almost conscious of a sort of intellectual measurement, has surely a
much greater resemblance to the perceptions, which we term _acquired_,
than to those which are _immediate_. In vision, for example, when the
original power of that sense has been strengthened and enriched, by the
acquisitions which it is capable of receiving from other sources, we
see a long line of distance before us; and the _small_ distances with
which we are familiar, we distinguish with sufficient accuracy; but, in
our visual measurement of _greater_ distances, we are almost certain
to err, taking often the less for the greater, and the greater for the
less. It is precisely the same in touch. When a small body, which we
have never seen, is pressed upon our hand, we are able, if its surface
be square, or circular, or of any other form, with which we are well
acquainted, to determine its figure, without much hesitation; because
we have learned, tactually, to distinguish these regular figures.
But, in endeavouring to determine, in this manner, by touch alone,
the figure of any irregular body, less familiar to us, though, as a
direct object of sense, if touch be the sense of figure, it should
be equally and as immediately tangible as the most regular form, we
feel a hesitation of the same sort, as when we attempt to ascertain by
our eye, the exact distance of a remote object. To know extension or
figure, is to know, not one point merely in the surface of a body, but
many continuous points; and if, when the surface, is circular, we know
these continuous points, and their relation to each other, immediately
on pressure, we must know, as immediately, the same points and their
relations, though the surface comprehending them, instead of being
circular, should be of an outline more irregular. We certainly cannot
know this irregular surface to have any extension at all, unless we
know some parts of it; and, when the pressure is uniform from every
point, and the organ of touch uniform, on which the pressure is made,
it would be absurd to suppose, that we know fifty, or eighty, of the
hundred points which form the impressing surface, but cannot determine
its figure, because we are ignorant of the twenty of fifty remaining
points; when these remaining points are acting on our organ of touch,
in exactly the same manner as the fifty or eighty which we know, and
when, if the surface containing merely the same number of points, had
been circular, or of any other single form, as familiar to us, the
whole hundred points would have been known to us equally and at once.
When our perceptions of form, then, are so various and irregular, and
are more or less quick and precise, exactly as the shape which we
endeavour to determine, has more or less resemblance to shapes that are
familiar to us, it does not seem too bold an inference to conclude,
that the knowledge of figure, which, as all extension that is capable
of being perceived by us, must have some boundary, is nothing more
than the knowledge of extension, is not the state of mind originally
and immediately subsequent to affections of our organs of touch, any
more than the perception of distance is the state of mind originally
and immediately subsequent to affections of our organ of sight; and
the very striking analogy of these two cases, it will be of great
importance for you to have constantly in view; as it will render it
less difficult for you to admit many circumstances, with respect to
touch, which you might otherwise have been slower to conceive. That we
should seem to perceive _extension_ immediately by touch, though touch
originally, and of itself, could not have afforded this perception,
will not then appear more wonderful, than the apparently immediate
perception of _distance_ by the eye, which, of itself, originally
afforded us no perception of that sort; nor the impossibility of
feeling a body, without the notion of it, as extended, be more
wonderful than the similar impossibility of separating colour from
extension, in the case of distant vision. Above all, the analogy is
valuable, as shewing the closeness and indissolubleness of the union,
which may be formed of feelings that have in themselves no resemblance.
What common properties, could we have conceived in vision, and that
absolute blindness, which has never had a single sensation from light!
and, yet, it is worthy of remark, that the perceptions of the blind,
in consequence of this singular power of association, form truly the
most important part of those very perceptions of vision, of which, as
a whole, they are unfortunately deprived. We do not merely see with our
eyes, what we may have felt with our hands; but our eyes, in the act of
vision, have borrowed, as it were, those very sensations.
The proof, that our perception of extension by touch, is not an
original and immediate perception of that sense, is altogether
independent of the success of any endeavour which may be made, to
discover the elements of the compound perception. It would not be less
true, that touch does not afford it, though we should be incapable of
pointing out any other source, from which it can be supposed to be
derived. Of the difficulty of the attempt, and the caution with which
we should venture to form any conclusion on the subject, I have already
spoken. But the analysis, difficult as it is, is too interesting not to
be attempted, even at the risk, or perhaps I should rather say, with
the very great probability, of failure.
In such an analysis, however, though we are to proceed with the
greatest caution, it may be necessary to warn you, that it is a part
of this very caution, not to be easily terrified, by the appearance of
paradox, which the result of our analysis may present. This appearance
we may be certain, that any analysis which is at all accurate must
present, because the very object of the analysis is to shew, that
sensations, which appear simple and direct, are not simple,--that
our senses, in short, are not fitted, of themselves, to convey that
information, which they now appear, and through the whole course of
our memory have appeared to us instantly to convey. It is very far,
indeed from following, as a necessary consequence, that every analysis
of our sensations which affords a paradoxical result, is, therefore, a
just one--for error may be extravagant in _appearance_ as well as in
_reality_. But it may truly be regarded as a necessary consequence,
that every accurate and original analysis of our sensations must afford
a result, that, as first stated, will appear paradoxical.