123 MENTAL EVOLUTION IN ANIMALS. 



such qualities pertain to temperature, hardness, softness, 

 roughness, smoothness, and other qualities appealing to the 

 sense of touch, as well as qualities appealing to the senses of 

 smell, taste, and hearing. In the case of these more universal 

 qualities, the part which the mind takes in the process of 

 cognizing them as belonging to the objects is immediate and 

 automatic, and, as Mr. Sully observes, " may be supposed to 

 answer to the most constant and therefore the most deeply 

 organized connections of experience." 



The third step in the advance of Perception consists in 

 the mental grouping of objects with reference to their quali- 

 ties, as when we associate the coo]ness, taste, &c, of a 

 particular fruit with its size, form, and colour. Here the 

 more frequently a certain class of qualities has been con- 

 joined with another class in past experience, the more readily 

 or automatically is the perceptive association established ; but 

 in cases where the conjunction of qualities has not been so 

 frequently or so constantly met with in past experience, we 

 are able by reflection to recognize the perceptive association 

 "as a kind of intellectual working up of the materials 

 supplied us by the past." 



A further development of the perceptive faculty is re- 

 quired to meet cases in which the qualities of objects have 

 become too numerous or complex to be all perceived simulta- 

 neously. In meeting such cases the faculty in question, 

 while perceiving some of the qualities through sensation, 

 supplements the immediate information so derived with 

 information derived from previously formed knowledge ; the 

 qualities which are not recognized immediately through sen- 

 sation are inferred. Thus, in my perception of a closed book 

 I have no doubt that the covers are filled with a number of 

 printed pages, although none of these pages are actually 

 objects of present sensation. Or, if I hear a savage growl, I 

 immediately infer the presence of an object presenting so 

 complex a group of unseen qualities as are collectively com- 

 prised in a dangerous dog. In a later chapter I shall have to 

 dwell more minutely on this, which I may term the inferential 

 stage of perception, and I shall therefore not deal more with 

 it at present. 



It will be evident that the various stages which I have 

 named in the development of Perception shade into one 

 another, so as not really to be distinguishable as separate 



