To a large extent we are misled by the impressive prominence of the visual data. In vision we are presented with a system of inter-related and simultaneously occurring sensations which we find by experience to be the sure and certain indicators of the potent obstructions which our activity encounters. For this reason we habitually make use of the visual sign as the guide and instrument of our exertional activity, and this habitual use leads us to regard the visual presentation as the essential form of Reality. However sure we are that that is a false view, it yet is very difficult to retrace our steps and re-enter the elemental darkness which involves the blind. The philosophic value of the interpretation of Experience by the blind ought therefore to be very great. Observations made on the experiences of the blind and of those to whom vision has been restored are not very numerous, but many of these recorded by Plainer, the friend of Leibniz, and others are of the highest value, and remarkably confirm the view for which we have been contending. 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.