Psychology of Animals. 199 



treatment before the Darwinian era. In fact, the prob- 

 lems of the psychical life of animals were in most 

 cases deliberately left alone by many of the Biology and 

 most competent pre- Darwinian biologists, Psychology. 

 who pretended to regard them either as quite out- 

 side their province, or as altogether beyond solution. 

 Not a little of this assertion of "intellectual preserves" 

 still remains. Of late, however, biologists have begun 

 to rescue the subject from the credulity of the ama- 

 teur and the frequent dogmatism of the philosopher. 

 This has been prompted partly by the recent advances 

 in regard to the physiological aspects of human psy- 

 chology, and partly by the development of the evolution- 

 theory, which has not only convinced us of the unity 

 of nature, but has directly raised many psychological 

 questions. A discussion of Darwin's theory of sexual 

 selection, for instance, necessarily demands some psy- 

 chological analysis, as Darwin himself recognized by 

 his work on the Expression of the Emotions. 



Following Prof. Groos, we may distinguish a theolo- 

 gical, a metaphysical, and a more or less consistent 

 scientific stage in the history of opinion in regard to the 

 mental life of animals. 



The theological mood found a short and easy method 

 of getting rid of all difficulties by leaving the mental life 

 of animals directly in the hands of the Theolo ical 

 Creator. Of that as an ultimate statement interpreta- 

 the scientific investigator has no criticism, 

 for he himself ventures no ultimate explanations; it 

 amounts, however, to a refusal to consider the problem 

 scientifically, and it is to be feared that this sort of piety 

 has often served as a cloak for intellectual indolence. 



H. S. Reimarus, a shrewd observer, who published a 

 large work on Instincts in 1760, may be taken as an 

 early representative of theological interpretation; and 

 Romanes quotes a typical sentence from Addison: " I 

 look upon instinct as upon the principle of gravitation 

 in bodies, which is not to be explained by any known 

 qualities inherent in the bodies themselves, nor from 

 any laws of mechanism, but as an immediate impres- 

 sion from the first mover and the divine energy acting 



