1 02 Instinct and its Lessons 



of fresh design, but striking out that which is native to 

 them, with the unhesitating accuracy of a planet describ- 

 ing an ellipse. The force guiding such operations is 

 what we describe as instinct. Round this term many 

 controversies have raged, and rage still, and not least as 

 to its definition. For present purposes it may be 

 sufficiently described as a guiding light directed to a 

 practical conclusion, but not by means of premisses : 

 telling the what, but not the why : guiding correctly, but 

 not supplying the knowledge on which alone could a 

 correct judgment rationally be based. 



That there is such a guide can hardly be denied. 

 What man could do only with much elaborate training, 

 animals do unhesitatingly and at once ; and while it is 

 simply out of the question to suppose that they have 

 the conscious knowledge by which he would have to 

 steer, they arrive at the goal by a straighter and surer 

 path: 



Sure never to o'ershoot, but just to hit, 



While still too wide or short is human wit ; 



This, too, serves always ; Reason, never long ; 



One must go right ; the other may go wrong. 1 



To give in illustration an oft-quoted example. Wasps 

 of the genus called Sphex lay up with their eggs a store 

 of animal food for the benefit of their young when 

 hatched. It is desirable, from their point of view, that 

 the victim chosen for this unhappy function, should be 

 rendered helpless, but at the same time not killed, that 

 so the provisions may keep fresh. This is effected by 

 stinging him in one or more nerve centres, thus para- 

 lyzing him for motion, but not immediately affecting his 

 life. One species of Sphex, for instance, preys upon 

 Crickets, in which three nerve centres have to be thus 

 dealt with, to reach one of which the neck has to be 

 stretched back, while the others are minute spots in 

 other parts of the body. For a man to do this would 

 require the nicest knowledge of anatomy. Yet the 

 Sphex performs the operation with unhesitating accuracy. 

 1 Pope, Essay on Man, iii. 



