158 MENTAL EVOLUTION IN ANIMALS. 



i.e., by the violation of his ideas of uniformity in matters 

 psychological. It must be added, however, that I have tried 

 the same experiment on less intelligent and less sensitive 

 terriers with no other effect than causing them to bark at me. 

 I will only add that I believe the sense of the mysterious to 

 be the cause of the dread which many animals show of 

 thunder. I am led to think this, because I once had a setter 

 which never heard thunder till he was eighteen months old, 

 and on then hearing it I thought he was about to die of 

 fright, as I have seen other animals do under various circum- 

 stances. And so strong was the impression which his extreme 

 terror left behind, that whenever afterwards he heard the 

 boom of distant artillery practice, mistaking it for thunder, 

 he became a pitiable object to look at, and, if out shooting, 

 would endeavour to bury himself or bolt home. After having 

 heard real thunder on two or three subsequent occasions, his 

 dread of the distant cannon became greater than ever; so 

 that eventually, though he keenly enjoyed sport, nothing 

 would induce him to leave his kennel, lest the practice might 

 begin when he was at a distance from home. But the keeper, 

 who had a large experience in the training of dogs, assured 

 me if I allowed this one to be taken to the battery in order 

 that he might learn the true cause of the thunder-like noise, 

 he would again become serviceable in the field. The animal, 

 however, died before the experiment was made."* 



Thus I think we may safely set down the sense of the 

 mysterious as thus undoubtedly displayed by intelligent dogs 

 — and also, I may add, by many horses when going along a 

 dark road, hearing strange sounds, or seeing unaccustomed 

 sights — to the effects of imagination in suggesting vague pos- 

 sibilities ill circumstances perceived to be unusual; just as 

 with children under similar circumstances the undefined 

 imagination of possible harm springing out of such circum- 

 stances in some unthought-of manner, engenders that feeling 

 of unreasonable dread which we may in both cases call a 

 sense of the mysterious. 



* That sucli would have been the case, however, I have little doubt, for 

 on one occasion when a number of apples were being shot out of bags upon 

 1h> wooden floor of an apple-room, the sound in the house as each bag was 

 shot closely resembled that of distant thunder. The setter, therefore, became 

 terribly alarmed ; but when I took him to the apple-room and showed him 

 the real cause of the noise, his dread entirely left him, and on again returning 

 to the house he listened to the rumbling with all cheerfulness. 



