ACTIONS OF ANIMALS 351 



Lastly, although the motive power of movements and actions, as 

 also their directive cause, are exclusively internal, we must not, as 

 has been done,^ Umit the original or prompting cause of these acts 

 to internal impressions, with the view of attributing all acts of inteUi- 

 gence to external impressions ; a slight knowledge of the facts is 

 enough to show that in both cases the causes, which stimulate 

 actions, are sometimes internal and sometimes external, and yet 

 that they do actually give rise to impressions which only act 

 internally. 



According to the common notion attached to the word instinct, it 

 is regarded as a torch which lights and guides animals in their actions, 

 and which is for them what reason is for us. Nobody has shown that 

 instinct may be a force that induces action, nor that it does induce 

 action without any intervention of the will but only under the control 

 of acquired propensities. 



The view of Cabanis that instinct arises from internal impressions, 

 while reasoning is the produce of external sensations, cannot be justified. 

 It is in ourselves that we feel ; our impressions can only be internal ; 

 and the sensations of external objects, derived from our special senses, 

 cannot produce in us any but internal impressions. 



When my dog is out for a walk and sees in the distance another 

 animal of his own species, he undoubtedly experiences a sensation 

 from that external object through the intermediary of sight. There- 

 upon his inner feehng, aroused by the impression received, guides his 

 nervous fluid in the direction of a tendency acquired in all the indi- 

 viduals of his race ; by a kind of involuntary impulse, his first move- 

 ment is towards the dog that he sees. This is an act of instinct, 

 excited by an external object, and many others of the same kind 

 may similarly be carried out. 



With regard to these phenomena, of which we find so many examples 

 in animal organisation, it seems to me that a true and clear idea of 

 their cause can only be found when we have recognised : (1) That 

 the inner feehng is a very powerful generahsed feehng, which has the 

 faculty of exciting and controlUng the movements of the free part 

 of the nervous fluid and of making the animal carry out various actions ; 

 (2) that this inner feehng is capable of being moved either by acts of 

 inteUigence culminating in a will to act, or by sensations which evoke 

 needs which in their turn immediately excite it, so that it guides the 

 productive force of actions in the direction of some acquired propensity 

 without the co-operation of any act of will. 



There are thus two kinds of causes which may move the inner 

 feeling, viz. those depending on intellectual operations, and those 

 I Rioherand, Phyaiologie, voJ. ii., p. 151. 



