210 The Outline of Science 



ship or nest-building, in hunting or preparing the food, it looks 

 as if the starting of the routine activity also "rang up" the higher 

 centres of the brain and put the intelligence on the qui vive, ready 

 to interpose when needed. So the twofold caution is this: (1) 

 We must not depreciate the creature too much if, in unusual cir- 

 cumstances, it acts in an ineffective way along lines of behaviour 

 which are normally handed over to instinct; and (2) we 

 must leave open the possibility that even routine instinctive be- 

 haviour may be suffused with awareness and backed by en- 

 deavour. 



2 



A Useful Law 



But how are we to know when to credit the animal with intel- 

 ligence and when with something less spontaneous? Above all, 

 how are we to know when the effective action, like opening the 

 mouth the very instant it is touched by food in the mother's beak, 

 is just a physiological action like coughing or sneezing, and when 

 there is behind it a mind at work? The answer to this question 

 is no doubt that given by Prof. Lloyd Morgan, who may be called 

 the founder of comparative psychology, that we must describe 

 the piece of behaviour very carefully, just as it occurred, without 

 reading anything into it, and that we must not ascribe it to a 

 higher faculty if it can be satisfactorily accounted for in terms of 

 a lower one. In following this principle we may be sometimes 

 niggardly, for the behaviour may have a mental subtlety that we 

 have missed ; but in nine cases out of ten our conclusions are likely 

 to be sound. It is the critical, scientific way. 



Bearing this law in mind, let us take a survey of the emer- 

 gence of mind among backboned animals. 



Senses of Fishes 



Fishes cannot shut their eyes, having no true lids; but the 

 eyes themselves are very well developed and the vision is acute, 



