2 Chapter I. 



very different from the faculty of human beings. 

 These opponents, as Romanes, Ziegler, etc., agree with 

 us in deeming it unscientific and ridiculous to explain, 

 as Brehm does, the adaptive activity that proceeds from 

 the sensitive knowledge of animals by the "animals' 

 own understanding." With true scientists, therefore, 

 the gist of the argument will turn on the following two 

 questions : First, is human "intelligence" essentially 

 different from that of the animal, or only different in 

 degree? Secondly, is it possible or not, that the human 

 mind could have developed from the animal faculty of 

 sensation ? 



But before commencing our comparative psychic 

 investigation, it is of the utmost importance to establish 

 some short and clear notions, according to which we 

 shall have to decide, whether certain animal actions are 

 instinctive or intelligent. True, nowadays, writers are 

 not fond of exact definitions in this very line of science. 

 "Why, everybody knows what is meant by instinct and 

 intelligence; therefore, we need not tire our readers 

 with philosophical definitions." In these, or in similar 

 terms, they are wont to introduce their essays. How- 

 ever, this is fishing in troubled waters. No wonder, 

 then, that after the perusal of such a "scientific exam- 

 ination," the reader is at a loss to see what the author 

 has proven ; for the author was at a loss himself. 



Any reasoning man, much more any naturalist, who 

 earnestly desires to investigate, and not to humanise 

 the psychic faculties of the animal, will therefore agree 

 with us in demanding a clear psychological analysis. 

 Only those who assert with Alfred Brehm, that the 

 notion of "instinct" is missing in their vocabulary, and 



