certainly can seem, as first stated, more absurd than the assertion,
that we see, not with our eyes merely, but chiefly by the medium
of another organ, which the blind possess in as great perfection
as ourselves, and which, at the moment of vision, may perhaps be
absolutely at rest. It must not surprise you, therefore, though the
element which seems to me to form the most important constituent of our
notion of extension should in like manner, as first stated to you, seem
a very unlikely one.
This element is our feeling of _succession_, or time--a feeling, which
necessarily, involves the notion of divisibility or series of parts,
that is so essential a constituent of our more complex notion of
matter,--and to which notion of continuous divisibility, if the notion
of resistance be added, it is scarcely possible for us to imagine, that
we should not have acquired, by this union, the very notion of physical
extension,--that which has parts, and that which resists our effort to
grasp it.
That _memory_ is a part of our mental constitution, and that we are
thus capable of thinking of a series of feelings, as successive to
each other, the experience of every moment teaches us sufficiently.
This succession frequently repeated, suggests immediately, or implies
the notion of length, not metaphorically, as is commonly said, but
as absolutely as extension itself: and, the greater the number of
the successive feelings may have been, the greater does this length
appear. It is not possible for us to look back on the years of our
life, since they form truly a progressive series, without regarding
them as a sort of length, which is more distinct indeed, the nearer
the succession of feelings may be to the moment at which we consider
them, but which, however remote, is still felt by us as _one continued
length_, in the same manner, as when, after a journey of many hundred
miles, we look back, in our memory, on the distance over which we
have passed, we see, as it were, a long track of which some parts,
particularly the nearer parts, are sufficiently distinct, but of which
the rest seems lost in a sort of distant obscurity. The line of our
long journeying--or, in other words, that almost immeasurable line of
plains, hills, declivities, marshes, bridges, woods,--to endeavour to
comprehend which in our thought, seems an effort as fatiguing as the
very journey itself--we know well, can be divided into those various
parts:--and, in like manner, the progressive line of time--or, in
other words, the continued succession, of which the joy, the hope, the
fragrance, the regret, the melody, the fear, and innumerable other
affections of the mind, were parts, we feel that we can mentally
divide into those separate portions of the train. Continuous length
and divisibility, those great elementary notions of space, and of
all that space contains, are thus found in every succession of our
feelings. There is no language in which time is not described as long
or short,--not from any metaphor--for no mere arbitrary metaphor can be
thus universal, and inevitable, as a form of human thought--but because
it is truly impossible for us to consider succession, without this
notion of progressive divisibility attached to it: and it appears to us
as absurd to suppose, that by adding, to our retrospect of a week, the
events of the month preceding, we do not truly lengthen the succession,
as it would be to suppose, that we do not lengthen the line of actual
distance, by adding, to the few last stages of a long journey, the many
stages that preceded it.
It is this spreading out of life into a long expanse, which allows
man to create, as it were, his own world. He cannot change, indeed,
the scene of external things. But this may be said, in one sense, to
be the residence only of his corporeal part. It is the moral scene in
which the spirit truly dwells; and this adapts itself, with harmonious
loveliness, or with horror as suitable, to the character of its pure or
guilty inhabitant. If but a single moment of life,--a physical _point_,
as it were, of the long line--could be reviewed at once, conscience
would have little power of retribution. But he who has lived, as man
should live, is permitted to enjoy that best happiness which man can
enjoy,--to behold, in one continued series, those years of benevolent
wishes or of heroic suffering, which are at once his merit and his
reward. He is surrounded by his own pure thoughts and actions, which,
from the most remote distance, seem to shine upon him wherever his
glance can reach; as in some climate of perpetual summer, in which
the inhabitant sees nothing but fruits and blossoms, and inhales only
fragrance, and sunshine, and delight. It is in a moral climate as
serene and cloudless, that the destined inhabitant of a still nobler
world moves on, in that glorious track, which has heaven before, and
virtue and tranquillity behind;--and in which it is scarcely possible
to distinguish, in the immortal career, when the earthly part has
ceased, and the heavenly begins.
Is it in _metaphor_ only, that a youth and maturity, and old age of
guilt, seem to stretch themselves out in almost endless extent, to
that eye which, with all its shuddering reluctance, is still condemned
to gaze on them,--when, after the long retrospect seems finished,
some fraud, or excess, or oppression, still rises and adds to the
dreadful line--and when eternity itself, in all the horrors which it
presents, seems only a still longer line of the same dreadful species,
that admits of no other measure, than the continued sufferings, and
remembrance, and terrors that compose it!
It is a just and beautiful observation of an ancient Stoic, that _time_
which is _past_ is like something consecrated to the gods, over which
fortune and mortality have no longer any power, and that, dreadful
as it must be to the wicked, to whom their own memory is an object
of terror, it still, to the virtuous, offers itself as a consolation
or joy--not in single moments like the present hour, but in all that
long series of years which rises before us, and remains with us at
our bidding. “Ille qui multa ambitiosè cupiit, superbè contempsit,
insidiosè decepit, avarè rapuit, prodigè effudit,--necesse est memoriam
suam timeat. Atqui hæc est pars temporis nostri sacra ac dedicata,
omnes humanos casus supergressa, extra regnum fortunæ subducta; quam
non inopia, non metus, non morborum incursus exagitat. Hæc nec turbari
nec eripi potest; perpetua ejus et intrepida possessio est. Singuli
tantùm dies, et hi per momenta, præsentis sunt: at præteriti temporis
omnes, cum jusseris aderunt, ad arbitrium tuum se inspici ac detineri
patientur.”
By those, who can look back on years that are long past, and yet
say, that the continued progress, or the length and the shortness
of time, are only _metaphorical_ expressions, it might be said with
equal justness, that the roundness of a sphere, is a metaphor, or the
angularity of a cube. We do not more truly consider the one as angular
and the other as round, than we consider the time to be continuously
progressive, in which we considered, first the one figure, and then
the other, and inquired into the properties of each. That which is
progressive must have _parts_. Time, or succession, then involves
the very notions of longitudinal extension and divisibility, and
involves these, without the notion of any thing external to the mind
itself;--for though the mind of man had been susceptible only of
joy, grief, fear, hope, and the other varieties of internal feeling,
_without_ the possibility of being affected by external things, he
would still have been capable of considering these feelings, as
successive to each other, in a long continued progression, divisible
into separate parts. The notions of length, then, and of divisibility,
are not confined to external things, but are involved, in that very
memory, by which we consider the series of the past,--not in the memory
of distant events only, but in those first successions of feeling, by
which the mind originally became conscious of its own permanence and
identity. The notion of time, then, is precisely coeval with that of
the mind itself; since it is implied in the knowledge of succession, by
which alone, in the manner formerly explained to you, the mind acquires
the knowledge of its own reality, as something more than the mere
sensation of the present moment.
Conceiving the notion of time, therefore, that is to say of feelings
past and present, to be thus one of the earliest notions which the
infant mind can form, so as to precede its notions of external things,
and to involve the notions of length and divisibility, I am inclined
to reverse exactly the process commonly supposed; and, instead of
deriving the measure of time from extension, to derive the knowledge
and original measure of extension from time. That one notion or feeling
of the mind may be united indissolubly with other feelings, with which
it has frequently coexisted, and to which, but for this coexistence, it
would seem to have no common relation, is sufficiently shown by those
phenomena of vision to which I have already so frequently alluded.
In what manner, however, is the notion of time peculiarly associated
with the simple sensation of touch, so as to form, with it, the
perception of extension? We are able, in the theory of vision, to
point out the coexistence of sensations which produce the subsequent
union; that renders the perception of distance apparently immediate.
If a similar coexistence of the original sensations of touch, with the
notion of continued and divisible succession, cannot be pointed out
in the present case, the opinion which asserts it, must be considered
merely as a wild and extravagant conjecture.
The source of such a coexistence is not merely to be found, but is at
least as obvious, as that which is universally admitted in the case of
vision.
Before I proceed, however, to state to you, in what way I conceive
the notion to be acquired, I must again warn you of the necessity of
banishing, as much as possible, from your view of the mind of the
infant in this early process, all those notions of external things,
which we are so apt to regard as almost original in the mind, because
we do not remember the time, when they arose in our own. As we know
well, that there are external things, of a certain form, acting on
our organs, which are also of a certain form, it seems so very simple
a process, to perceive extension--that is to say, to know that there
exist without us those external forms, which really exist--that to
endeavour to discover the mode, in which extension, that now appears so
obvious a quality of external things, is perceived by us, seems to be
a needless search, at a distance, for what is already before our very
eyes. And it will be allowed, that all this would, indeed, be very easy
to a mind like ours, after the acquisitions of knowledge which it has
made; but the difficulty of the very question is, how the mind of the
infant makes these acquisitions, so as to become like ours. You must
not think of a mind, that has any knowledge of things external, even
of its own bodily organs, but of a mind simply affected with certain
feelings, and having nothing but these feelings to lead it to the
knowledge of things without.
To proceed, then,--The hand is the great organ of touch. It is composed
of various articulations, that are easily moveable, so as to adapt
it readily to changes of shape, in accommodation to the shape of the
bodies which it grasps. If we shut our hand gradually, or open it
gradually, we find a certain series of feelings, varying with each
degree of the opening or closing, and giving the notion of succession
of a certain length. In like manner, if we gradually extend our arms,
in various directions, or bring them nearer to us again, we find
that each degree of the motion is accompanied with a feeling that is
distinct, so as to render us completely conscious of the progression.
The gradual closing of the hand, therefore, must necessarily give a
succession of feelings,--a succession, which, of itself, might, or
rather must, furnish the notion of length, in the manner before stated,
the length being different, according to the degree of the closing; and
the gradual stretching out of the arm gives a succession of feelings,
which, in like manner, must furnish the notion of length,--the length
being different according to the degree of the stretching of the arm.
To those who have had opportunities of observing infants, I need not
say, how much use, or rather what constant use, the future inquirer
makes of his little fingers and arms; by the frequent contraction
of which, and the consequent renewal of the series of feelings
involved in each gradual contraction, he cannot fail to become so
well acquainted with the progress, as to distinguish each degree of
contraction, and, at last, after innumerable repetitions, to associate
with each degree the notion of a certain length of succession. The
particular contraction, therefore, when thus often repeated, becomes
the representative of a certain length, in the same manner as shades of
colour, in vision become ultimately representative of distance,--the
same principle of association, which forms the combination in the one
case, operating equally in the other.
In these circumstances of acquired knowledge,--after the series of
muscular feelings, in the voluntary closing of the hand, has become
so familiar, that the whole series is anticipated and expected, as
soon as the motion has begun,--when a ball, or any other substance, is
placed for the first time in the infant's hand, he feels that he can
no longer perform the usual contraction,--or, in other words, since
he does not fancy that he has muscles which are contracted, he feels
that the usual series of sensations does not follow his will to renew
it,--he knows how much of the accustomed succession is still remaining;
and the notion of this particular length, which was expected, and
interrupted by a new sensation, is thus associated with the particular
tactual feeling excited by the pressure of the ball,--the greater or
less magnitude of the ball preventing a greater or less portion of
the series of feelings in the accustomed contraction. By the frequent
repetition of this tactual feeling, as associated with that feeling,
which attends a certain progress of contraction, the two feelings at
last flow together, as in the acquired perceptions of vision; and when
the process has been repeated with various bodies innumerable times, it
becomes, at last, as impossible to separate the mere tactual feeling,
from the feeling of length, as to separate the whiteness of a sphere,
in vision, from that convexity of the sphere, which the eye, of itself,
would have been forever incapable of perceiving.
As yet, however, the only dimension of the knowledge, of which we have
traced the origin, is mere length; and it must still be explained,
how we acquire the knowledge of the other dimensions. If we had had
but one muscle, it seems to me very doubtful, whether it would have
been possible for us, to have associated with touch any other notion
than that of mere length. But nature has made provision, for giving us
a wider knowledge, in the various muscles, which she has distributed
over different parts, so as to enable us to perform motions in various
directions at the same instant, and thus to have coexisting series
of feelings, each of which series was before considered as involving
the notion of length. The infant bends one finger gradually on the
palm of his hand; the finger, thus brought down, touches one part of
the surface of the palm, producing a certain affection of the organ
of touch, and a consequent sensation; and he acquires the notion
of a certain length, in the remembered succession of the muscular
feelings during the contraction:--he bends another finger; it, too,
touches a certain part of the surface of the palm, producing a certain
feeling of touch, that coexists and combines, in like manner, with the
remembrance of a certain succession of muscular feelings. When both
fingers move together, the coexistence of the two series of successive
feelings, with each of which the mind is familiar, gives the notion of
coexisting lengths, which receive a sort of unity, from the proximity
in succession of the tactual feelings in the contiguous parts of the
palm which they touch,--feelings, which have before been found to be
proximate, when the palm has been repeatedly pressed along a surface,
and the tactual feelings of these parts, which the closing fingers
touch at the same moment, were always immediately successive,--as
immediately successive, as any of the muscular feelings in the series
of contraction. When a body is placed in the infant's hand, and its
little fingers are bent by it as before, sometimes one finger only is
impeded in its progress, sometimes two, sometimes three,--and he thus
adds to the notion of mere length, which would have been the same,
whatever number of fingers had been impeded, the notion of a certain
number of proximate and coexisting lengths, which is the very notion of
breadth; and with these, according as the body is larger or smaller,
is combined always the tactual affection produced by the pressure of
the body, on more, or fewer, of the interior parts of the palm, and
fingers, which had before become, of themselves, representative of
certain lengths, in the manner described; and the concurrence of these
three varieties of length, in the single feeling of resistance, in
which they all seem to meet, when an incompressible body is placed
within the sphere of the closing fingers,--however rude the notions
of concurring dimensions may be, or rather must be, as at first
formed,--seems at least to afford the rude elements, from which, by
the frequent repetition of the feeling of resistance, together with
the proximate lengths, of which it has become representative, clearer
notions of the kind may gradually arise.
The progressive contractions of the various muscles which move the
arms, as affording similar successions of feelings, may be considered
in precisely the same light, as sources of the knowledge of extension;
and, by their motion in various directions, at the same time with
the motion of the fingers, they concur powerfully, in modifying, and
correcting, the information received from these. The whole hand is
brought, by the motion of the arm, to touch one part of the face or
body; it is then moved, so as to touch another part, and, with the
frequent succession of the simple feelings of touch, in these parts, is
associated the feeling of the intervening _length_, derived from the
sensations that accompanied the progressive contraction of the arm.
But the motion is not always the same; and, as the same feeling of
touch, in one part, is thus followed by various feelings of touch in
different parts, with various series of muscular feelings between, the
notion of length in various _directions_, that is to say, of length in
various series commencing from one power, is obtained in another way.
That the knowledge of extension, or in other words, the association
of the notion of succession with the simple feelings of touch, will
be rude and indistinct at first, I have already admitted; but it will
gradually become more and more distinct and precise: as we can have no
doubt, that the perception of distance by the eye, is, in the first
stages of visual association, very indistinct, and becomes clearer
after each repeated trial. For many weeks or months, all is confusion
in the visual perceptions, as much as in the tactual and muscular.
Indeed, we have abundant evidence of this continued progress of vision,
even in mature life, when, in certain professions that require nice
perceptions of distance, the power of perception itself, by the gradual
acquisitions which it obtains from experience, seems to unfold itself
more and more, in proportion to the wants that require it.
The theory of the notion of extension, of which I have now given you
but a slight outline, might, if the short space of these Lectures
allowed sufficient room, be developed with many illustrations, which it
is now impossible to give to it. I must leave you, in some measure, to
supply these for yourselves.
It may be thought, indeed, that the notion of _time_, or _succession_,
is, in this instance, a superfluous incumbrance of the theory, and
that the same advantage might be obtained, by supposing the muscular
feelings themselves, independently of the notion of their succession,
to be connected with the notion of particular lengths. But this
opinion, it must be remarked, would leave the difficulty precisely as
before; and sufficient evidence in confutation of it, may be found
in a very simple experiment, which it is in the power of any one to
make. The experiment I cannot but consider as of the more value,
since it seems to me,--I will not say _decisive_, for that is too
presumptuous a word,--but strongly _corroborative_ of the theory,
which I have ventured to propose; for it shows, that, even after
all the acquisitions, which our sense of touch has made, the notion
of extension is still modified, in a manner the most striking and
irresistible, by the mere change of accustomed _time_. Let any one,
with his eyes shut, move his hand, with moderate velocity, along a part
of a table, or any other hard smooth surface, the portion, over which
he presses, will appear of a certain length; let him move his hand more
rapidly, the portion of the surface pressed will appear _less_; let him
move his hand _very slowly_, and the length, according to the degree of
the slowness, will appear increased, in a most wonderful proportion.
In this case, there is precisely the same quantity of muscular
contraction, and the same quantity of the organ of touch compressed,
whether the motion be rapid, moderate, or slow. The only circumstance
of difference is the time, occupied in the succession of the feelings;
and this difference is sufficient to give complete diversity to the
notion of length.
If any one, with his eyes shut, suffer his hand to be guided by
another, very slowly along any surface unknown to him, he will find it
impossible to form any accurate guess as to its length. But it is not
necessary, that we should be previously unacquainted with the extent
of surface, along which the motion is performed; for the illusion
will be nearly the same, and the experiment, of course, be still
more striking, when the motion is along a surface with which we are
perfectly familiar, as a book which we hold in our hand, or a desk at
which we are accustomed to sit.
I must request you, not to take for granted the result which I have
now stated, but to repeat for yourselves an experiment, which it
is so very easy to make, and which, I cannot but think is so very
important, as to the influence of _mere difference of time_, in our
estimation of _longitudinal extent_. It is an experiment, tried,
unquestionably, in most unfavourable circumstances, when our tactual
feelings, representative of extension, are so strongly fixed, by the
long experience of our life; and yet, even now, you will find, on
moving your hand, slowly and rapidly, along the same extent of surface,
though with precisely the same degree of pressure in both cases, that
it is as difficult to conceive the extent, thus slowly and rapidly
traversed, to be the same, as it is difficult to conceive the extent
of visual distance to be exactly the same, when you look alternately
through the different ends of an inverted telescope. If when all other
circumstances are the same, the different visual feelings, arising from
difference of the mere direction of light, be representative of length,
in the one case,--the longer or shorter succession of time, when all
other circumstances are the same, has surely as much reason to be
considered as representative of it, in the other case.