30 Chapter III. 



quainted with any nest of its own species, collect after 

 pairing little stalks and blades of grass and similar ma- 

 terial for a warm nest, in which its fledglings are to be 

 hatched; for neither by experience nor by thought or 

 reflection could it know before its first season of breed- 

 ing, that it would even lay eggs, and that these eggs 

 would have to be hatched, in order to produce a new 

 generation of its own kind. It is due to instinct, when 

 a dog that suffers from tape-worm eats Artemisia ab- 

 sinthium, although it otherwise never touches this plant ; 

 for a study of medicine would be requisite to hit upon 

 such a suitable treatment by its own experience. It is 

 instinct, finally, that causes the new-bonrbabe to express 

 its feeling of hunger by crying and seeking its mother's 

 breast; 1 for it could not possibly have previously recog- 

 nized by experience or its own thinking the suitableness 

 of its cries and its attempts to suck. 



What is it, then, that essentially characterises these 

 different instinctive actions? It is the circumstance 

 that their suitableness lies beyond the perception of the 

 respective agent. The unconscious suitableness (adap- 

 tiveness) is, consequently, the essential criterion of 

 instinctive, in contradistinction to intelligent actions. 



Not without purpose was it pointed out in each of 

 the previous examples that the respective agent not 

 only lacked experimental knowledge of the suitableness 

 of its acts, but that it likewise was unable to attain that 

 knowledge by means of its own deliberate reflections. 

 Animal psychology considers in a one-sided manner 

 only the former point of view, and neglects the latter. 



*) This example was used by St. Thomas of Aquin (2, dist. 20, q. 

 2, a. 2 ad 5). 



