Suppose the above-mentioned blind person by his touch perceives a man to
stand erect. Let us inquire into the manner of this. By the application
of his hand to the several parts of a human body he had perceived
different tangible ideas, which being collected into sundry complex ones,
have distinct names annexed to them. Thus one combination of a certain
tangible figure, bulk, and consistency of parts is called the head,
another the hand, a third the foot, and so of the rest: all which complex
ideas could, in his understanding, be made up only of ideas perceivable
by touch. He had also by his touch obtained an idea of earth or ground,
towards which he perceives the parts of his body to have a natural
tendency. Now, by ERECT nothing more being meant than that perpendicular
position of a man wherein his feet are nearest to the earth, if the blind
person by moving his hand over the parts of the man who stands before him
perceives the tangible ideas that compose the head to be farthest from,
and those that compose the feet to be nearest to, that other combination
of tangible ideas which he calls earth, he will denominate that man
erect. But if we suppose him on a sudden to receive his sight, and that
he behold a man standing before him, it is evident in that case he would
neither judge the man he sees to be erect nor inverted; for he never
having known those terms applied to any other save tangible things, or
which existed in the space without him, and what he sees neither being
tangible nor perceived as existing without, he could not know that in
propriety of language they were applicable to it.
97. Afterwards, when upon turning his head or eyes up and down to the
right and left he shall observe the visible objects to change, and shall
also attain to know that they are called by the same names, and connected
with the objects perceived by touch; then indeed he will come to speak of
them and their situation, in the same terms that he has been used to
apply to tangible things; and those that he perceives by turning up his
eyes he will call upper, and those that by turning down his eyes he will
call lower.
98. And this seems to me the true reason why he should think those
objects uppermost that are painted on the lower part of his eye: for by
turning the eye up they shall be distinctly seen; as likewise those that
are painted on the highest part of the eye shall be distinctly seen by
turning the eye down, and are for that reason esteemed lowest; for we
have shown that to the immediate objects of sight considered in
themselves, he would not attribute the terms HIGH and LOW. It must
therefore be on account of some circumstances which are observed to
attend them: and these, it is plain, are the actions of turning the eye
up and down, which suggest a very obvious reason why the mind should
denominate the objects of sight accordingly high or low. And without this
motion of the eye, this turning it up and down in order to discern
different objects, doubtless ERECT, INVERSE, and other the like terms
relating to the position of tangible objects, would never have been
transferred, or in any degree apprehended to belong to the ideas of
sight: the mere act of seeing including nothing in it to that purpose;
whereas the different situations of the eye naturally direct the mind to
make a suitable judgment of the situation of objects intromitted by it.
99. Farther, when he has by experience learned the connexion there is
between the several ideas of sight and touch, he will be able, by the
perception he has of the situation of visible things in respect of one
another, to make a sudden and true estimate of the situation of outward,
tangible things corresponding to them. And thus it is he shall perceive
by sight the situation of external objects which do not properly fall
under that sense.
100. I know we are very prone to think that, if just made to see, we
should judge of the situation of visible things as we do now: but we are
also as prone to think that, at first sight, we should in the same way
apprehend the distance and magnitude of objects as we do now: which hath
been shown to be a false and groundless persuasion. And for the like
reasons the same censure may be passed on the positive assurance that
most men, before they have thought sufficiently of the matter, might have
of their being able to determine by the eye at first view, whether
objects were erect or inverse.
101. It will, perhaps, be objected co our opinion that a man, for
instance, being thought erect when his feet are next the earth, and
inverted when his head is next the earth, it doth hence follow that by
the mere act of vision, without any experience or altering the situation
of the eye, we should have determined whether he were erect or inverted:
for both the earth itself, and the limbs of the man who stands thereon,
being equally perceived by sight, one cannot choose seeing what part of
the man is nearest the earth, and what part farthest from it, i.e.
whether he be erect or inverted.
102. To which I answer, the ideas which constitute the tangible earth and
man are entirely different from those which constitute the visible earth
and man. Nor was it possible, by virtue of the visive faculty alone,
without superadding any experience of touch, or altering the position of
the eye, ever to have known, or so much as suspected, there had been any
relation or connexion between them. Hence a man at first view would not
denominate anything he saw earth, or head, or foot; and consequently he
could not tell by the mere act of vision whether the head or feet were
nearest the earth: nor, indeed, would we have thereby any thought of
earth or man, erect or inverse, at all: which will be made yet more
evident if we nicely observe, and make a particular comparison between,
the ideas of both senses.
103. That which I see is only variety of light and colours. That which I
feel is hard or soft, hot or cold, rough or smooth. What similitude, what
connexion have those ideas with these? Or how is it possible that anyone
should see reason to give one and the same name to combinations of ideas
so very different before he had experienced their coexistence? We do not
find there is any necessary connexion betwixt this or that tangible
quality and any colour whatsoever. And we may sometimes perceive colours
where there is nothing to be felt. All which doth make it manifest that
no man, at first receiving of his sight, would know there was any
agreement between this or that particular object of his sight and any
object of touch he had been already acquainted with: the colours,
therefore, of the head would to him no more suggest the idea of head than
they would the idea of foot.
104. Farther, we have at large shown (VID. sect. 63 and 64) there is no
discoverable necessary connexion between any given visible magnitude and
any one particular tangible magnitude; but that it is entirely the result
of custom and experience, and depends on foreign and accidental
circumstances that we can by the perception of visible extension inform
ourselves what may be the extension of any tangible object connected with
it. Hence it is certain that neither the visible magnitude of head or
foot would bring along with them into the mind, at first opening of the
eyes, the respective tangible magnitudes of those parts.
105. By the foregoing section it is plain the visible figure of any part
of the body hath no necessary connexion with the tangible figure thereof,
so as at first sight to suggest it to the mind. For figure is the
termination of magnitude; whence it follows that no visible magnitude
having in its own nature an aptness to suggest any one particular
tangible magnitude, so neither can any visible figure be inseparably
connected with its corresponding tangible figure: so as of itself and in
a way prior to experience, it might suggest it to the understanding. This
will be farther evident if we consider that what seems smooth and round
to the touch may to sight, if viewed through a microscope, seem quite
otherwise.
106. From all which laid together and duly considered, we may clearly
deduce this inference. In the first act of vision no idea entering by the
eye would have a perceivable connexion with the ideas to which the names
EARTH, MAN, HEAD, FOOT, etc., were annexed in the understanding of a
person blind from his birth; so as in any sort to introduce them into his
mind, or make themselves be called by the same names, and reputed the
same things with them, as afterwards they come to be.
107. There doth, nevertheless, remain one difficulty, which perhaps may
seem to press hard on our opinion, and deserve not to be passed over: for
though it be granted that neither the colour, size, nor figure of the
visible feet have any necessary connexion with the ideas that compose the
tangible feet, so as to bring them at first sight into my mind, or make
me in danger of confounding them before I had been used to, and for some
time experienced their connexion: yet thus much seems undeniable, namely,
that the number of the visible feet being the same with that of the
tangible feet, I may from hence without any experience of sight
reasonably conclude that they represent or are connected with the feet
rather than the head. I say, it seems the idea of two visible feet will
sooner suggest to the mind the idea of two tangible feet than of one
head; so that the blind man upon first reception of the visive faculty
might know which were the feet or two, and which the head or one.
108. In order to get clear of this seeming difficulty we need only
observe that diversity of visible objects doth not necessarily infer
diversity of tangible objects corresponding to them. A picture painted
with great variety of colours affects the touch in one uniform manner; it
is therefore evident that I do not by any necessary consecution,
independent of experience, judge of the number of things tangible from
the number of things visible. I should not, therefore, at first opening
my eyes conclude that because I see two I shall feel two. How, therefore,
can I, before experience teaches me, know that the visible legs, because
two, are connected with the tangible legs, or the visible head, because
one, is connected with the tangible head? The truth is, the things I see
are so very different and heterogeneous from the things I feel that the
perception of the one would never have suggested the other to my
thoughts, or enabled me to pass the least judgment thereon, until I had
experienced their connexion.
109. But for a fuller illustration of this matter it ought to be
considered that number (however some may reckon it amongst the primary
qualities) is nothing fixed and settled, really existing in things
themselves. It is entirely the creature of the mind, considering either
an idea by itself, or any combination of ideas to which it gives one
name, and so makes it pass for an unit. According as the mind variously
combines its ideas the unit varies: and as the unit, so the number, which
is only a collection of units, doth also vary. We call a window one, a
chimney one, and yet a house in which there are many windows and many
chimneys hath an equal right to be called one, and many houses go to the
making of the city. In these and the like, instances it is evident the
unit constantly relates to the particular draughts the mind makes of its
ideas, to which it affixes names, and wherein it includes more or less as
best suits its own ends and purposes. Whatever, therefore, the mind
considers as one, that is an unit. Every combination of ideas is
considered as one thing by the mind, and in token thereof is marked by
one name. Now, this naming and combining together of ideas is perfectly
arbitrary, and done by the mind in such sort as experience shows it to be
most convenient: without which our ideas had never been collected into
such sundry distinct combinations as they now are.
110. Hence it follows that a man born blind and afterwards, when grown
up, made to see, would not in the first act of vision parcel out the
ideas of sight into the same distinct collections that others do, who
have experienced which do regularly coexist and are proper to be bundled
up together under one name. He would not, for example, make into one
complex idea, and thereby esteem an unit, all those particular ideas
which constitute the visible head or foot. For there can be no reason
assigned why he should do so, barely upon his seeing a man stand upright
before him. There crowd into his mind the ideas which compose the visible
man, in company with all the other ideas of sight perceived at the same
time: but all these ideas offered at once to his view, he would not
distribute into sundry distinct combinations till such time as by
observing the motion of the parts of the man and other experiences he
comes to know which are to be separated and which to be collected
together.
111. From what hath been premised it is plain the objects of sight and
touch make, if I may so say, two sets of ideas which are widely different
from each other. To objects of either kind we indifferently attribute the
terms high and low, right and left, and suchlike, denoting the position
or situation of things: but then we must well observe that the position
of any object is determined with respect only to objects of the same
sense. We say any object of touch is high or low, according as it is more
or less distant from the tangible earth: and in like manner we denominate
any object of sight high or low in proportion as it is more or less
distant from the visible earth: but to define the situation of visible
things with relation to the distance they bear from any tangible thing,
or VICE VERSA, this were absurd and perfectly unintelligible. For all
visible things are equally in the mind, and take up no part of the
external space: and consequently are equidistant from any tangible thing
which exists without the mind.
112. Or rather, to speak truly, the proper objects of sight are at no
distance, neither near nor far, from any tangible thing. For if we
inquire narrowly into the matter we shall find that those things only are
compared together in respect of distance which exist after the same
manner, or appertain unto the same sense. For by the distance between any
two points nothing more is meant than the number of intermediate points:
if the given points are visible the distance between them is marked out
by the number of the interjacent visible points: if they are tangible,
the distance between them is a line consisting of tangible points; but if
they are one tangible and the other visible, the distance between them
doth neither consist of points perceivable by sight nor by touch, i.e. it
is utterly inconceivable. This, perhaps, will not find an easy admission
into all men's understanding: however, I should gladly be informed
whether it be not true by anyone who will be at the pains to reflect a
little and apply it home to his thoughts.
113. The not observing what has been delivered in the two last sections
seems to have occasioned no small part of the difficulty that occurs in
the business of erect appearances. The head, which is painted nearest the
earth, seems to be farthest from it: and on the other hand the feet,
which are painted farthest from the earth, are thought nearest to it.
Herein lies the difficulty, which vanishes if we express the thing more
clearly and free from ambiguity, thus: how comes it that to the eye the
visible head which is nearest the tangible earth seems farthest from the
earth, and the visible feet, which are farthest from the tangible earth
seem nearest the earth? The question being thus proposed, who sees not
the difficulty is founded on a supposition that the eye, or visive
faculty, or rather the soul by means thereof, should judge of the
situation of visible objects with reference to their distance from the
tangible earth? Whereas it is evident the tangible earth is not perceived
by sight: and it hath been shown in the two last preceding sections that
the location of visible objects is determined only by the distance they
bear from one another; and that it is nonsense to talk of distance, far
or near, between a visible and tangible thing.
114. If we confine our thoughts to the proper objects of sight, the whole
is plain and easy. The head is painted farthest from, and the feet
nearest to, the visible earth; and so they appear to be. What is there
strange or unaccountable in this? Let us suppose the pictures in the fund
of the eye to be the immediate objects of the sight. The consequence is
that things should appear in the same posture they are painted in; and is
it not so? The head which is seen seems farthest from the earth which is
seen; and the feet which are seen seem nearest to the earth, which is
seen; and just so they are painted.
115. But, say you, the picture of the man is inverted, and yet the
appearance is erect: I ask, what mean you by the picture of the man, or,
which is the same thing, the visible man's being inverted? You tell me it
is inverted, because the heels are uppermost and the head undermost?
Explain me this. You say that by the head's being undermost you mean that
it is nearest to the earth; and by the heels being uppermost that they
are farthest from the earth. I ask again what earth you mean? You cannot
mean the earth that is painted on the eye, or the visible earth: for the
picture of the head is farthest from the picture of the earth, and the
picture of the feet nearest to the picture of the earth; and accordingly
the visible head is farthest from the visible earth, and the visible feet
nearest to it. It remains, therefore, that you mean the tangible earth,
and so determine the situation of visible things with respect to tangible
things; contrary to what hath been demonstrated in sect. 111 and 112. The
two distinct provinces of sight and touch should be considered apart, and
as if their objects had no intercourse, no manner of relation one to
another, in point of distance or position.
116. Farther, what greatly contributes to make us mistake in this matter
is that when we think of the pictures in the fund of the eye, we imagine
ourselves looking on the fund of another's eye, or another looking on the
fund of our own eye, and beholding the pictures painted thereon. Suppose
two eyes A and B: A from some distance looking on the pictures in B sees
them inverted, and for that reason concludes they are inverted in B: but
this is wrong. There are projected in little on the bottom of A the
images of the pictures of, suppose, man, earth, etc., which are painted
on B. And besides these the eye B itself, and the objects which environ
it, together with another earth, are projected in a larger size on A.
Now, by the eye A these larger images are deemed the true objects, and
the lesser only pictures in miniature. And it is with respect to those
greater images that it determines the situation of the smaller images: so
that comparing the little man with the great earth, A judges him
inverted, or that the feet are farthest from and the head nearest to the
great earth. Whereas, if A compare the little man with the little earth,
then he will appear erect, i.e. his head shall seem farthest from, and
his feet nearest to, the little earth. But we must consider that B does
not see two earths as A does: it sees only what is represented by the
little pictures in A, and consequently shall judge the man erect. For, in
truth, the man in B is not inverted, for there the feet are next the
earth; but it is the representation of it in A which is inverted, for
there the head of the representation of the picture of the man in B is
next the earth, and the feet farthest from the earth, meaning the earth
which is without the representation of the pictures in B. For if you take
the little images of the pictures in B, and consider them by themselves,
and with respect only to one another, they are all erect and in their
natural posture.
117. Farther, there lies a mistake in our imagining that the pictures of
external objects are painted on the bottom of the eye. It hath been shown
there is no resemblance BETWEEN the ideas of sight and things tangible.
It hath likewise been demonstrated that the proper objects of sight do
not exist without the mind. Whence it clearly follows that the pictures
painted on the bottom of the eye are not the pictures of external
objects. Let anyone consult his own thoughts, and then say what affinity,
what likeness there is between that certain variety and disposition of
colours which constitute the visible man, or picture of a man, and that
other combination of far different ideas, sensible by touch, which
compose the tangible man. But if this be the case, how come they to be
accounted pictures or images, since that supposes them to copy or
represent some originals or other?
118. To which I answer: in the forementioned instance the eye A takes the
little images, included within the representation of the other eye B, to
be pictures or copies, whereof the archetypes are not things existing
without, but the larger pictures projected on its own fund: and which by
A are not thought pictures, but the originals, or true things themselves.
Though if we suppose a third eye C from a due distance to behold the fund
of A, then indeed the things projected thereon shall, to C, seem pictures
or images in the same sense that those projected on B do to A.
119. Rightly to conceive this point we must carefully distinguish between
the ideas of sight and touch, between the visible and tangible eye; for
certainly on the tangible eye nothing either is or seems to be painted.
Again, the visible eye, as well as all other visible objects, hath been
shown to exist only in the mind, which perceiving its own ideas, and
comparing them together, calls some PICTURES in respect of others. What
hath been said, being rightly comprehended and laid together, doth, I
think, afford a full and genuine explication of the erect appearance of
objects; which phenomenon, I must confess, I do not see how it can be
explained by any theories of vision hitherto made public.
120. In treating of these things the use of language is apt to occasion
some obscurity and confusion, and create in us wrong ideas; for language
being accommodated to the common notions and prejudices of men, it is
scarce possible to deliver the naked and precise truth without great
circumlocution, impropriety, and (to an unwary reader) seeming
contradictions; I do therefore once for all desire whoever shall think it
worth his while to understand what I have written concerning vision, that
he would not stick in this or that phrase, or manner of expression, but
candidly collect my meaning from the whole sum and tenor of my discourse,
and laying aside the words as much as possible, consider the bare notions
themselves, and then judge whether they are agreeable to truth and his
own experience, or no.
121. We have shown the way wherein the mind by mediation of visible ideas
doth perceive or apprehend the distance, magnitude and situation of
tangible objects. We come now to inquire more particularly concerning the
difference between the ideas of sight and touch, which are called by the
same names, and see whether there be any idea common to both senses. From
what we have at large set forth and demonstrated in the foregoing parts
of this treatise, it is plain there is no one selfsame numerical
extension perceived both by sight and touch; but that the particular
figures and extensions perceived by sight, however they may be called by
the same names and reputed the same things with those perceived by touch,
are nevertheless different, and have an existence distinct and separate
from them: so that the question is not now concerning the same numerical
ideas, but whether there be any one and the same sort of species of ideas
equally perceivable to both senses; or, in other words, whether
extension, figure, and motion perceived by sight are not specifically
distinct from extension, figure, and motion perceived by touch.