Essays Towards a Theory of Knowledge | Page 5

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.
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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 d��calque 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 qualit��s 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 and utilises in his discursive employment of the idea of any physical thing is what we have ventured to call its dynamic significance. And the very careful analysis which M. Villey has made of the mental conceptions of the blind clearly shows that in their case he has reached exactly the same conclusion.
Our fundamental conceptions of the external world are therefore derived from and are built up out of the data of