Essays Towards a Theory of Knowledge | Page 5

data of
Vision. The sounds which we hear, the odours which we smell, are the
immediate result of certain undulations affecting the appropriate organ
of sensation. We refer these to the object in which the undulations
originate. In like manner a light which we see is referred to its objective
luminous source. But light also and in addition is reflected from, and
thus reveals the presence of the whole body of our resistant
environment. Hence is derived the coloured presentation of Vision to
which the character of extensity attaches. Nothing similar takes place in
the case of the other distantial sensations. If sonorous undulations
excited vibration in every resistant object of the environment they
would undoubtedly come to arrange themselves in an order resembling
the extensity suggested by Vision, though the slower rate of
transmission of sound would detract from the practical simultaneity in
the effect which, as we have seen, largely accounts for the perception
of visual extensity. The universal diffusion of sunlight is also a
determining factor.

* * * * *
The matter becomes still clearer when we contrast the experience of
vident men with what we have been able to learn of the experiences of
the blind. Nowhere have we found this aspect of the question discussed
with the same clearness and ability as by M. Pierre Villey in his
recently published essay, Le Monde des Aveugles--Part III.
The blind man, as he remarks, requires representations in order to
command his movements. We must then penetrate the mind of the
blind and ascertain what are his representations. Are they, he asks,
muscular images combined by temporal relations, or are they images of
a spatial order? He replies without hesitation: Both, but, above all,
spatial images. It is clear, he says, that the modalities of the action of
the blind are explained by spatial representations. These must be
derived from touch. What, then, can be the spatial representations
which arise from touch? The blind, he says, are often asked, How do
you figure to yourself such and such an object, a chair, a table, a
triangle? M. Villey quotes Diderot as affirming that the blind cannot
imagine. According to Diderot, images require colour, and colour being
totally wanting to the blind the nature of their imagination was to him
inconceivable. The common opinion, says M. Villey, is entirely with
Diderot. It does not believe that the blind can have images of the
objects around him. The photographic apparatus is awanting and the
photograph cannot therefore be there.
Diderot was a sensationalist. For this school, as Villey remarks, l'image
est le décalque de la sensation, and he refers not merely to Condillac
the friend of Diderot but to his continuator Taine whose dictum we
have already quoted.
Diderot attempts to solve the problem by maintaining that tactual
sensations occupy an extended space which the blind in thought can
add to or contract, and in this way equip himself with spatial
conceptions.
There would, on this view, as M. Villey remarks, be a complete
heterogeneity between the imagination of the blind and that of the

vident. M. Villey denies this altogether. He affirms that the image of an
object which the blind acquires by touch readily divests itself of the
characters of tactual sensation and differs profoundly from these. He
takes the example of a chair. The vident apprehends its various features
simultaneously and at once; the blind, by successive tactual palpations.
But he maintains that the evidence of the blind is unanimous on this
point, that once formed in the mind the idea of the chair presents itself
to him immediately as a whole,--the order in which its features were
ascertained is not preserved, and does not require to be repeated. Indeed,
the idea divests itself of the great bulk of the tactual details by which it
was apprehended, whilst the muscular sensations which accompanied
the act of palpation never seek to be joined with the idea. This
divestiture of sensation proceeds to such an extent that there is nothing
left beyond what M. Villey calls the pure form. The belief in the reality
of the object he refers to its resistance. The origin of each of these is
exertional. The features upon which the mind dwells, if it dwells upon
them at all, are les qualités qui sont constamment utiles pour la
pratique--in a word, the dynamic significance of the thing.
We may remark that much the same is true of the ideas of the vident. In
ordinary Discourse we freely employ our ideas of external objects
without ever attempting a detailed reproduction of the visual image.
Such a reproduction would be both impracticable and unnecessary, and
would involve such a sacrifice of time as to render Discourse altogether
impossible. All that the Mind of the vident ordinarily grasps