262 MIND IN EVOLUTION CHAP. 



qualities of a person. We human beings know our friends 

 in a very different way. A man is many-sided, and to 

 know him is to respond to him with a many-sided under- 

 standing. In their degree the higher animals have this 

 knowledge of their masters. The ape, the dog, and the 

 elephant in a lesser degree the horse, and even the cat- 

 notoriously "understand one." The dog follows with 

 anxious sympathy the subtlest variations of mood. 

 " Knowledge " of this kind makes attachment possible 

 as an emotion. It may be said that in attributing emotions 

 of this kind to the higher animals, we base ourselves, after 

 all, on certain modes of reaction. But, if we do, our 

 interpretation is borne out by agreement with the facts. 

 The cat that looks angry also acts like an angry being, 

 and scepticism on this point may prove practically 

 dangerous. On the whole, we may say that knowledge 

 of individuals becomes possible at the level of intelligence 

 which we are discussing, and that the appropriate emotions 

 of attachment, dislike, jealousy, and so forth, are to all 

 appearance expressed at this stage. 



A certain mutual understanding seems also to be implied 

 in many features of animal play. No doubt play is 

 instinctive, and the activities of play are often called 

 forth by a stimulus acting upon hereditary structure ; but 

 observers tell us of many instances in which animals of 

 different species, even where one might naturally be the 

 prey of the other, learn to play fearlessly together. 1 It 

 is difficult to think that a game could arise under these 

 circumstances, or be maintained without degenerating into 

 a serious fight or hunt, unless each animal takes what the 

 other does as meant in play, and not as meant in earnest. 

 It must know, that is to say, that the threat to bite is not 

 going to be followed by a real bite. In a word, each 

 animal must judge of what the other is going to do. 2 



The view that an animal not merely reacts to objects, 

 but knows them, is thus confirmed by evidence from more 

 than one source. We have seen some ground for thinking 



1 See Groos, pp. 128, 143. 



2 For the degree of mutual understanding in courtship, see Groos, 

 P- 253- 



