324 Animal Life and Intelligence. 



see it involves a somewhat subtle analysis. We perceive 

 it to be yellow, round, resistant ; and then, isolating these 

 qualities, we reach conceptions, of yellowness, roundness, 

 and resistance, quite apart from oranges. Throughout our 

 description the terms we used were very largely terms 

 denoting classified isolates. 



Lastly, having enormously increased our knowledge by 

 this process of isolation, we proceed to build in the know- 

 ledge thus gained to the structure of our constructs. This 

 is the third and last stage in construction. The first stage 

 is the formation of indefinite constructs by immediate 

 association ; the second is the definition of constructs by 

 examination ; and the third is the completion of constructs 

 by synthesis. 



And the further this process of analysis and isolation 

 is carried, the more we are, so to speak, floated off from 

 the immediate objects of sense into the higher regions of 

 abstract thought. Furthermore, by recombining our iso- 

 lates in new modes and under new relations, we reach the 

 splendid results of constructive imagination. 



In the brief description which I have now given of our 

 mental processes, I have for the most part avoided certain 

 terms which are current in the science of psychology. It 

 will be well here to say a few words concerning these words 

 and their use. The process of sensation is sometimes 

 defined as the mere reception of a sense-stimulus. But 

 it is more convenient, and more in accordance with common 

 usage, to call the simple result of a stimulus an impres- 

 sion, and to apply the term "sensation " to the discrimina- 

 tion and recognition of the impressions as of such and such 

 a quality. Sensation, then, is the reception and discrimina- 

 tion of impressions which result from certain modes of 

 influence (stimuli) brought to bear on our organization. 

 Viewed in this way, therefore, even sensation involves a 

 distinct reaction of the mind ; it implies the first stage of 

 mental activity. But when the sensations are given 

 objective significance, when they suggest the existence of 

 an object-world without us, they enter the field of percep- 



