MAN THE INTERPRETER OF NATURE. 201 



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 aUke by physicists and physiologists, that colour does 

 not exist as such in the object itself; which has merely the power 

 of reflecting or transmitting a certain number of millions of un- 

 dulations 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 dis- 

 tinguished, 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 fiot 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 experience.* 



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

 composite perception of form which we derive from the visual 

 sense alone is so complete, that we seldom require to fall back 

 upon 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 pictures formed by any solid or projecting object 

 upon our two retince, that (as Sir Charles VVheatstone's admirable 

 investigations have shown) we ordinarily derive through the sight 



* Thus, in a recently recorded case in which sight was imparted by opera- 

 tion to a young woman who had been bhnd from birth, but who had never- 

 theless learned 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. 



