THE COMPOSITION OF MIND 



grouping of them as like or unlike. In per- 

 ceiving an apple, for example, " the bulk is per- 

 ceived 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 percep- 

 tion, therefore, consists in the recognition of 

 sundry attributes as like sundry attributes pre- 

 viously 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 impressions 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 repeated and careful com- 

 parison of visual impressions with muscular and 

 tactual impressions is the patient enabled to 

 discover, by the eye alone, that all the objects 



