DII. xv.] THE COMPOSITION OF MIND. 107 



inference from the known value of a side in the one to the 

 desired value of the corresponding side in the other, the act 

 i$ an act of reasoning. But when, on taking up two similar 

 sea-shells, we recognize them in their totality as belonging 

 to an oyster or some other familiar mollusk, the act is an 

 act of classification, commonly so called. In other words, 

 if the perception of similarity is followed by the thought 

 of one or more of the like relations which make up simi 

 larity, we have an act of reasoning ; but if it is followed 

 by the thought of other objects presenting like relations 

 of similarity to the one now perceived, we have an act of 

 classification. 



But, closely related as these two mental operations are 

 now seen to be, we have not yet disclosed the full extent to 

 which they are related. Not only is classification involved 

 in every act of reasoning or inference, but reasoning or 

 inference is involved in every act of classification. Not only 

 does reasoning consist in the grouping of relations as like or 

 unlike, but the classification of things can go on only through 

 the grouping of relations as like or unlike. To illustrate 

 this, let us take a further downward step, and consider a 

 mental operation apparently much simpler than those hitherto 

 treated. Let us consider what is implied by the perception 

 Df an object. 



It is admitted on all sides that the perception of an object 

 necessarily implies the recognition of the object as this or 

 hat, as like certain objects, and as unlike certain other 

 objects. Every act of perception, therefore, involves classi 

 fication. We cannot even name a chair without implying 

 the existence of a group of objects which the chair resembles; 

 and the essential element in the perception of a chair is not 

 the reception of a group of visual or tactual impressions, but 

 the interpretation of these impressions as like other ante 

 cedent impressions which, taken together, constitute the 

 consciousness of the presence of a chair. And this is as 



