Instinct. 93 



Instinct may be defined to be that principle of 

 action implanted in the animal by which he provides 

 for himself, and the continuance of the species. It 

 controls the animal. He acts under its guidance 

 always in a uniform manner under the same condi- 

 tions, and without instruction. If there comes to 

 be any variation or apparent change in this instinct, 

 it is for a specific purpose ; and the change or modi- 

 fication of instinct is as much under law as the 

 change in form and structure by which new varieties 

 are originated from the same species. It is this 

 uniformity of instinct that gives uniformity of action 

 to the same species of animals all over the world. 

 It determines what the animal shall be as a sentient, 

 voluntary agent. This description might be enlarg- 

 ed, but I am inclined to think it covers instinct 

 proper. 



Although it is difficult to draw the dividing line, 

 we must recognise in some animals an intelligence 

 distinct from instinct, and higher ; an intelligence 

 by which they enter into certain relations to man, 

 comprehend his wishes, understand his commands, 

 and form attachments to him. They must have a 

 degree of intelligence to understand so fully as some 

 of them do intelligent man. If any choose to say 

 that we have here simply higher manifestations of 

 instinct, then we must enlarge our definition ; for 

 many things comprehended and done by domesti- 

 cated animals are neither necessary for their own 

 existence, nor for the continuance of the species. 

 When the watch-dog guards his master's treasure, it 



