Mental Processes in Animals. 373 



to indicate what seem to me the advantages of the usage 

 (legitimate or illegitimate) I adopt. 



I repeat, then, that the introduction of the process of 

 analysis appears to me to constitute a new departure in 

 psychological evolution ; that the process differs generically 

 from the process of perceptual construction on which it is 

 grafted. And I hold that, this being so, we should mark 

 the departure in every way that we can. I mark it by a 

 restriction of the word "intelligence" to the inferences 

 formed in the field of perception ; and the use of the word 

 " reason " when conceptual analysis supervenes. Whether 

 I am justified in so doing, whether my usage is legitimate 

 or not, I must leave others to decide. But, adopting this 

 usage, I see no grounds for believing that the conduct of 

 animals, wonderfully intelligent as it is, is, in any instances 

 known to me, rational. 



I say that the introduction of the process of analysis 

 appears to me to constitute a new departure. This, how- 

 ever, must not be construed to involve any breach of 

 continuity. 



I do not believe that there is or has been any such 

 breach of continuity. Take a somewhat analogous case. 

 I regard the introduction of aerial respiration in animal 

 life as a new departure. Organisms which had hitherto 

 been water-breathers became air-breathers. But I do not 

 imagine that there was any breach of continuity in respira- 

 tion. The tadpole begins life as a water-breather only; 

 the frog into which he develops is an air-breather; but 

 there is no breach of continuity between the one state and 

 the other. So, too, the little child dwells in the perceptual 

 sphere ; the man into whom he develops is capable of 

 conceptual thought ; but there is no breach of continuity 

 in the mental life of the child. It is true that, with all 

 our talk on the subject, we cannot say exactly when in this 

 continuous mental life the new departure is made. But 

 this is no proof whatever that there is no new departure. 

 In a sigmoidal curve there is a new departure where the 

 convex passes into the concave. We may find it difficult 



