SENSORY AND RATIONAL DISCRIMINATION 125 



which the sensitive organism comes into contact. 

 This contrast is bold and sharp in outline. We first 

 say, it is with the man as with the animal ; we next 

 say, it is not with the animal as it is with the man. 

 What is the difference between sensibility, common to 

 man and the star-fish, and rational discrimination 

 belonging only to man ? It appears first in the 

 contrast between successive sensory impressions and 

 consciousness of difference between past and present 

 impressions. This contrast visibly widens when 

 rational power carries its exercise further, accumulat 

 ing knowledge by generalisation, giving fixedness 

 to knowledge by use of names, and attaining to 

 wider inductions, recognising general laws of Nature. 

 Sensibility as a life-experience is precisely the same 

 through the whole scale of life from the mollusc to man. 

 Whether the elements in which life subsists be water 

 or air, sensibility is stirred by movement of this 

 element. So it is with the functions of special senses. 

 Certain movements in the atmosphere distribute light, 

 others distribute sound; sensibility is the same in 

 kind for animal life in contact with these atmo 

 spheric movements. Whatever differences there may 

 be in terminal arrangements for the special senses, 

 all life possessed of such special sense depends for 

 sensibility on an optic or auditory nerve similar in 

 structure. The strength of evidence for continuity in 

 structure and function up the scale of organism, 

 largely increases the difficulty of reaching a scientific 

 explanation of rationality by reference to structure. 



What, then, is observation, as distinct from sensi 

 bility ? It is interpretation of sensory experience, 

 when using the senses for rational ends. It stands 



