Undoubtedly, so far as we are aware, the most valuable contribution to this aspect of the discussion is to be found in a little volume recently published in Paris under the title Le Monde des Aveugles. The author, M. Pierre Villey, is himself blind. In the interests of Science he has cast aside the delicacy and reserve which have generally prevented the blind from analysing or at least from discussing the import of their experiences. He is also fortunately possessed of a philosophic and highly cultivated intellect, and has not failed to make himself acquainted with the general course of metaphysical speculation.
The present writer has been in correspondence with M. Villey, whose conclusions remarkably confirm the view for which this essay contends, and he finds that M. Villey recognises the truth of that view. Individual quotations would only detract from the cumulative effect of his argument, but we may refer in particular to the interesting discussion as to the relations between the space concepts of the blind and those of the vident. The blind can be taught, and are taught, geometry, and can discuss and understand spatial and geometrical problems. The sensible furniture by which the spatial conceptions of the blind are denoted obviously cannot be visual, and are no doubt largely tactual, whilst on the other hand the vident utilise the visual data to the almost total exclusion of any other. There must therefore be some common measure by means of which a community is established between the spatial conceptions of the blind and those of the vident. M. Villey concludes and clearly shows that the common medium is to be found in the fact that our spatial conceptions are fundamentally based upon and are expressive of the discoveries of our exertional activity. Touch, in short, is an ambiguous term and includes both passive sensations and those forms of Activity which we describe when we use the term "feel" as a transitive verb. Just as we distinguish between seeing and looking or between hearing and listening, so should we distinguish between touch passive and touch active or palpation.
The view of Science which we have endeavoured to explain has received a notable confirmation from the establishment during the latter part of the nineteenth century of the scientific doctrine of Energy.[69:1]
The culmination of the scientific fabric of which Galileo and Newton laid the foundations was reached when it was demonstrated that the whole physical universe must be regarded as composed of Energy, either kinetic and actually undergoing transmutation from one form to another, or potential and quiescent yet containing within itself the quantifiable capacity of transformation. The objective correlatives of the different classes of sensible experiences are found to be different forms which this Energy assumes—the kinetic energy of a mass in motion, the radiant energy of Light, the energy of Heat, the potential energy of chemical separation, etc.—all these have now at length been shown to be forms of one real thing capable under appropriate conditions of being transmuted into each other and of which not only the inter-transmutability but the equivalent values can be calculated and have been found by experiment to be fixed and definite. Thus the mechanical equivalent of heat is a fixed and definite quantity. The Energy of a body in motion can be measured and stated in terms of mass and velocity.
The profound conception of Aristotle, under which Nature was regarded as a potent Energy containing within itself the capacity of generating the phenomenal World, has again been revived and realised—but with great additions. The theory in the hands of Science is now not only confirmed by incessant experiment, but the relation which it affirms between reality and phenomenon has been quantified.
Moreover, the actual operations under which the potential generates the actual have, so to say, been laid bare to view; and lastly, the inter-transmutability of all forms of Energy and its real unity have been established.
The doctrine has therefore received a confirmation of which Aristotle did not dream, and its explanation has at the same time received an illumination which his vague if profound adumbration could never afford. With this added support the true conception of human knowledge has received new strength. The theory is still, nevertheless, not to be grasped without a resolute effort of reflection. It involves an inversion of our everyday conceptions more radical than that which was demanded by the Copernican theory of astronomy, and we know that that theory—offered to and rejected by mankind before the beginning of the Christian era—had to wait through sixteen or seventeen hundred years before it secured an acceptance, at first grudging and even now not always adequate.
The ordinary metaphysical student has hitherto rather resented the idea that in order to a true solution of the problem of Knowledge he must acquaint himself with the fundamental conceptions of physics. Yet so it is. It may perhaps be hoped that when the first strangeness of the new position has disappeared the conditions may be accepted with greater readiness. At any rate, a correct apprehension of our fundamental conceptions of the world of our external experience is indispensable. No theory can wholly dispense with such conceptions. It is therefore essential that, however elementary, they should be clear and not contradictory. Philosophy has always vaguely realised and exacted as much. The need is now imperative.