108 COSMIG PHILOSOPHY. [pt. it. 



tniich an act of classification, as the act by virtue cf which 

 the naturalist would rank a newly-found horned and cloven- 

 hoofed mammal among the ruminants ; the only difference 

 being that in ordinary perception the act has been per- 

 formed so frequently as to have become automatic at an 

 early period of life, while in scientific classification the act 

 involves more or less conscious thinking, and comparison of 

 relations. 



Here, in this last clause, there is hinted what we are seek- 

 ing for. Not only in scientific classification, but in ordinary 

 perception also, tliere must go on a comparison of relations, 

 and a grouping of them as like or unlike. In perceiving an 

 apple, for example, " the bulk is perceived to be like the bulk 

 of apples in general ; the form like their forms ; the colour 

 like their colours ; the surface like their surfaces ; and so 

 on." For if the bulk were like that of a water-melon, or if 

 the shape were cubical, or if the colour were inky black, or if 

 the surface were covered with thorns, the object would not 

 be perceived to be an apple. The act of perception, there- 

 fore, consists in the recognition of sundry attributes as like 

 sundry attributes previously known, and as having relations 

 to one another like the relations between the before-known 

 attributes. This will appear still more clearly, when we 

 recollect what takes place in visual perception. It is well 

 known that the eye, unassisted by the muscular and tactual 

 senses, can take no cognizance of distance, shape, or solidity 

 — the only impressions which the retina receives are im- 

 pressions of colour, and indirectly of superficial extension. 

 It is because of this that infants reach out for the moon, 

 and that blind men, on first receiving sight, are unable 

 to distinguish between a round orange and a cubical block, 

 without feeling the surfaces of the two. Only after re- 

 peated and careful comparison of visual impressions with 

 muscular aud tactual impressions is the patient enabled 

 to discover, by the eye alone, that all the objects in the 



