ADDRESS. Ixxix 



resistance and of weight as properties common to all forms of Matter ; and 

 now that we have got rid of that idea of Light and Heat, Electricity and 

 Magnetism, as " imponderable fluids," which used to vex our souls in our 

 Scientific Childhood, and of which the popular term " Electric fluid " is a 

 " survival," we accept these properties as affording the practical distinction 

 between the "material" and the "immaterial." 



Turning, now, to that other great portal of Sensation, the Sight, through 

 which we receive most of the messages sent to us from the Universe around, 

 we recognize the same truth. Thus it is agreed alike by Physicists and 

 Physiologists, that Colour docs not exist as such in the object itself; which 

 has merely the power of reflecting or transmitting a certain number of 

 millions of undulations in a second; and these only produce that affection 

 of our consciousness which we call Colour, when they fall upon the retina of 

 the living Percipient. And if there be that defect either in the retina or in 

 the apparatus behind it, which we call " colour-blindness " or Daltonism, 

 some particular hues cannot be distinguished, or there may even be no power 

 of distinguishing any colour whatever. If we were all like Dalton, we should 

 see no difference, except in form, between ripe cherries hanging on a tree, 

 and the green leaves around them : if we were all affected with the severest 

 form of colour-blindness, the fair face of Nature would be seen by us as in 

 the chiaroscuro of an Engraving of one of Turner's Landscapes, not as in the 

 glowing hues of the wondrous Picture itself. And in regard to our Visual 

 conceptions it may be stated with perfect certainty, as the result of very 

 numerous observations made upon persons who have acquired sight for the 

 first time, that these do not serve for the recognition even of those objects 

 with which the individual had become most familiar through the Touch, 

 until the two sets of Sense-perceptions have been co-ordinated by expeiience*. 



When once this co-ordination has been effected, however, the composite 

 perception of Form which we derive from the Yisnal sense alone is so 

 complete, that we seldom require to fall back xipon the Touch for any further 

 information respecting that quality of the object. — So, again, while it is 

 from the co-ordination of the two dissimilar pictui'es formed by any solid 

 or projecting object upon our two retinae, that (as Sir Charles Wheat- 

 stone's admirable investigations have shown) we ordinarily derive through 

 the Sight alone a correct notion of its solid form, there is adequate evidence 

 that this notion, also, is a mental judgment based on the experience we have 

 acquired in early infancy by the consentaneous exercise of the Visual and 

 Tactile senses. 



Take, again, the case of those wonderful instruments by which our Visual 

 range is extended almost into the infinity of Space, or into the infinity of 

 Minuteness. It is the mental not the bodily eye, that takes cognizance of 

 what the Telescope and the Microscope reveal to us. For we should have 

 no well-grounded confidence in their revelations as to the %ml:nou'n, if we 

 had not first acquired experience in distinguishing the true from the false 

 by applying them to Icnown objects ; and every interpretation of what we see 

 through theii* instrumentality is a mental judgment as to the probable form, 



* Thu3, in a recently recorded case in which sight -was imparted by operation to a young 

 ■woman who Lad been blind from birth, but who had ncTevtheless leai-ned to work well 

 with her needle, when the pair of scissors she had been accustomed to use was placed 

 before her, though she described their shape, colour, and glistening metallic character, she 

 was utterly unable to recognize them as scissors until she put her finger on them, when 

 she at once named them, laughing at her own stupidity (as she called it) in not having 

 made them out before. 



