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.